You mentioned hip flexor stretching but little else in that department. Try some yoga poses - cat, cow, wag the tail, thread the needle (to stretch out your abductors), pigeon (same idea), lying knee hugs, lower body twist (lie flat on your back, bend knees about 90 degrees and using your right hand, press down on the outside of left knee; apply constant pressure and hold. Keep left shoulder blade on ground). And stretch your hamstrings/glutes/piriformis a lot!

Stretch, stretch, stretch. Try a yoga class. Strengthen your core's inner unit by doing pelvic tilt exercises, and focus on engaging the proper core muscles, especially the smaller, less used ones - if you're not doing "bird dog" as a core exercise, start. Learn how to engage your TVA when doing any exercise, including sitting at your desk. Get regular massage or become best friends with a foam roller or baseball/tennis/golf ball and work on massaging out knots to increase blood flow. Massage and stretch, back and forth, and repeat. Walk a lot and squeeze your glutes when you do.

Many people I know do lots of core exercises but they don't have the proper recruitment pattern so the overwork their bigger muscles and the smaller ones which connect to the spine don't get used enough, which causes disfunction. This is why you might see a bodybuilder with huge lats who gets back pain while standing over the sink brushing his teeth. Look for exercises to train the multifidus, erector spinae, and TVA in particular. Good luck.

I'm dealing with this as well. I've tried most of the things you have tried but the two things that have paid the most dividends in my low back health have been...

1. AM and PM yoga before and after work. I work out of hotels often and I wake very early. That gives me time to lay out the blanket, and sit in the floor doing basic yoga and holding each position for 1.5 - 2 minutes for about 3 repetitions of each stretch. Morning sessions take me about 20 minutes, evenings are maybe half that.

2. Hamstrings, hamstrings, hamstrings! Most low back pain comes from your hamstring being in a constantly relaxed state (sitting in a chair), and tightening up (tugging on your lumbars in the process). Spend more time stretching your hamstrings - here are a few that are good to start. I personally prefer the "wall" hamstring stretches while taking a hot shower, they seem to loosen up quite well with the added heat.

3. Take short walks on your lunch break, bring a very large glass of water (mine is 1 quart) and drink it constantly so you are either recycling (peeing) or refilling your glass every hour. Try to make sure you are at least getting a 5 minute period of standing/walking for every hour in your desk, 15 minutes would be optimal (but not the best if you work call center/help desk).

Good luck!

If the stuff you've been trying hasn't helped, you might have a structural defect or injury that needs medical attention. Some back pain can even be caused by stuff like kidney disease.

Another thing to consider is how your coordination-balance-muscular habit have been warped by the pain, or may have caused it. The only approach that deals directly with these matters is the Alexander Technique. (See the report from the British Medical Journal for a quick look).

http://www.stat.org.uk/pages/ateam.htm

The STAT website should link to teacher's organizations in your area. If you can't find a teacher nearby, contact the nearest one anyway, they may be able to put you in touch with an unlisted teacher in your neighborhood.

I've been doing Egoscue since October for major disk degenerative disease (the ortho I saw in Sept wanted to fuse basically my entire lumbar spine). Basically their premise is that back pain is from a misaligned spine, and the spine does what the postural muscles tell it to do. Fix/strengthen the postural muscles (not just the core) and you resolve the pain.

If you're near one of their centers, I'd recommend being guided, but note that it's not considered medical so insurance doesn't cover it. There are Egoscue books, so that may be an option as well. Basically Egoscue involves doing specific exercises pretty much every day. It's not like chiropractic (no immediate response), but over time, it definitely adds up. I went from being unable to walk 75 steps without pain to walking my first mile (today actually).

Another option you might want to consider is Esther Gokhale's posture method.

I'm not a fitness expert and I'm no chiropractor but what you're dealing with is 10 years of bad posture it's probably going to take a lot of patience, experimenting and testing.

First off I would double check this ergo checklist:

Secondly I would do these movement and do them often:

1. Deadlift

http://www.youtube.com/watch?v=MX8jgCFXYTU

1. Squat

http://www.youtube.com/watch?v=kawBY5p29fQ

Progression is important with these lifts; don't go out and try a 440 lbs pull right out of the gate.

The key is not focusing on your core, that's like putting a cast on a broken bone just on the break. What you want to do is strengthen all the muscles around your problem, that way the muscles around your problem area will support you and your new muscles will act as a brace.

FULL DISCLOSURE: This is just a "hack" from a fitness hack; you probably want to see a good Chiro or Occupational Therapist to find out what's really going on...

EDIT: I forgot to mention the mother of all powerlifts (IMHO): The Power Clean. This movement incorporates almost every huge muscle of your body, and if you can throw in a jerk or a push press at the end of the movement you are going to strengthen your entire body which in turn should reverse any weird posture quirk you might have.

Progression, progression, progression is important with this movement. Start with a weight that's in the range of 15%-20% of your max deadlift and measure and track progress.

If you could progress to BECOME A BEAST AT THE POWER CLEAN I can almost guarantee (I hate using the word, but that's how confident that I am) you are going to cure almost any core ailment or posture ailment.

The walk 5 miles is a great idea,this was also suggested by my surgeon. I would go to the college track almost every night, after work and knock out 20 walking laps. Here are some other things that have helped me.

-Vitamin D/ Magnesium/ K2. I assume your dealing with some type of degenerative disc disease and rather than treat the sympotom Im a fan of slow the progression of the disease. These absolutely need to be optimized, but dont expect a quick fix.

-Inversion tables, these can be had relatively cheap on Amazon and I recommend at least trying one.

-Also try and find somebody in your are who does accu-pressure or dynamic release method, I was able to gain some relief with this. Good luck.

Lastly, I hate to say it, but if my back is really screwed and and I cant get better on my own, one MELOXICAM and its better within two days and it stays that way for at least a month.

1)I highly recommend starting a yoga practice, but it's of the upmost importance to find a good teacher. Usually you can tell by how filled the class is and how many regulars there are, but not always.

2) Structural Integration AKA "Rolfing" would also be highly beneficial. This form of bodywork helps to envourage proper alignment

3) is possible that you may be dehydrated? Low back pain can often be a symptom of dehydration, try increasing your water if in doubt

My dad had this issue- he is an accountant, and has been sitting in a desk for years. The strengthening of his hip flexors made a really huge difference, under the guidance of a physiotherapist, and improving his posture when moving around. One of the easiest ways to improve his posture, he found, was to swap out his chair for an exercise ball in a stand. It's a great alternative to a standing desk (which he found impairs his productivity a lot, and because he's working with clients a lot he needs to be sitting with them).

I would personally look for a good physiotherapist, my dad has found his to be a lifesaver, he really took him step-by-step through what little exercises he should be doing when, how to keep a proper posture, and even helped him map out his office desk/system to make sure everything is optimal. Also, because my dad had caused pretty serious injury to his back from years of poor posture/sitting in a desk/playing hockey, it was important to have that professional support I think, so that he was able to speed up the healing process and get back to feeling mobile. It seems like you have most of the parts of the equation for back health, so it might be that you need the guidance of a professional. Or, maybe just give a different sitting device, such as the exercise ball, a shot before, they are pretty reasonably priced.

I also have a desk job (in the web design field) and suffered back pain from sitting all day. Then I tried a yoga ball and multiple walk breaks in my work day that last anywhere from 5-20 mins...and I havent noticed any major back pain since! I've been doing this for probably 3 or 4 weeks now. Moving around every 30 mins at work is a good idea that you're already doing too :)

Muscle Balance Therapy is what finally got my husband out of the desk job pit of pain. It is a self guided program, with specific strengthening and stretching exercises. I guess sitting at a desk causes some muscles to overtighten and others to become too weak, and most workouts target all muscles equally, tightening the already tight ones more while the loose ones tighten up, ending up with the more strength, but the same imbalance.

He did close to 3 hours a day of the stretches and exercises, I don't think you have to be that intense, but he was desperate, and things seemed to get significantly better within a month, and he is relatively pain free now, but does need to do maintenance exercises or it creeps back in.

Hi I blogged about proper desk setup the other day and thought you may find the video I made helpful. I also work a 9-5 job and can relate to your pains. Humans weren't designed to sit in a sedentary position all day.

Take a look at the link below and let me know if you have any questions

http://christiangolez.wordpress.com/2012/04/19/office-yoga-series-desk-setup/

Why cann't you try Actipatch here http://www.internationaldrugmart.com/over-the-counter-meds/actipatch.shtml. I used it for a year, and it worked well for me.

I have the same problem,and I have found chiropractors/acupuncture to be magical in fixing it. Also try swimming / flutter kicks to strengthen little muscles in your back. Sorry feel better!