UPDATE 8/29: So it's been around a month and a half since I posted this. Haven't had caffeine since this post, and due to the more stable energy levels that brings I feel a little better, though my energy levels still don't feel normal. My temperature is averaging 97.7, which is better than it's been though still well below my normal 98.6. My current COA is stay away from caffeine and go gluten/sugar-free and see where that leaves me in a couple months.
Let me just say first of all that I don't eat Paleo (although I'll give it a shot at some point). I'm asking this question here because after lurking a bit and being impressed by the community's enthusiasm for and knowledge of health, it seems I might find a reasonable answer here or at least get pointed in the right direction (already tried three doctors so far with no luck).
My problems started about a year ago (I'm now a 24-year-old male FWIW). I started having fairly severe (to me) pain and discomfort from my forearms down, especially in my hands (including carpal bossing in my right hand). The only major lifestyle change I could pinpoint was that I had started drinking coffee six months prior and had gotten up to a three cup/day habit; I also noticed that the numbness was worse depending on my coffee intake. After trying to quit a few times I tried switching to tea, but the problems persisted (just less severe because of less caffeine). Anyway, I didn't consume any caffeine at all for all of May and fell into a brain fog the whole month with no light in sight. I did notice, peculiarly, that I felt like my normal pre-coffee self for about the first fifteen to forty-five minutes after waking up each day, but went downhill after that. Cortisol?
So, with grad school looming, I caved and tried tea again for a week, then went a week or two off, then these past two weeks coffee and tea. What I've noticed is that even though I feel more awake and my cognition is in some sense improved, I feel more disoriented too now when I have either (esp. tea). To my medically-uneducated self it feels like the caffeine's stimulant properties are being overpowered by whatever negative effect it's having on my health. To top it all off I've noticed lately that my body temp. is pretty low (yesterday it was down to 96) and I've always been a solid 98.6er. I don't check my temp. frequently so it may have been like this for a few months, I dunno, but either way it's bizarre for me.
Any help? Guidance? Things I should ask a doctor about? The two things I keep coming across are hypothyroidism and adrenal fatigue, but RE the former I am quite the ectomorph (5'11", 120 lbs.), my TSH was normal at a recent check-up, and most of the physical symptoms don't seem to fit.
Now that I have an honest-to-God symptom (low body temp.) instead of vague I'm-tired/I-can't-focus complaints I'm pretty intent on cutting out the caffeine, because at the very least it doesn't seem to be helping.
TL;DR: 24-y/o thin guy; brain fog, but fairly alert first thing in the morning; low body temp.; maybe caffeine-related.