Yeah, ditch the fish oil. It makes me break out, and I've heard others say they have the same problem.

It makes me break out in a big way along my jawline.

It's actually quite easy to solve this. I worked for 6 months to get rid of chin acne, and for me it comes down to :

1. Stress.
2. Calcium & Vitamin D.
3. Nut consumption.

Ditch the nuts, relax, eat egg shells and go out into the sun. Do not underestimate calcium, it made a big difference in my overall health. Gelatin and bone broth help my chin acne a lot too.

I've had mild acne for the past ten years. Here's what I've been doing / going to try:

1. I stopped washing my face with anything besides water. The first week or two sucks because your skin will feel really oily. I'd frequently wipe my face down with a damp paper towel. Fortunately I was camping for my first week...and didn't worry about showering anyways.

2. I stopped washing my hair with shampoo. Mainly water and occasionally apple cider vinegar. This really helped clear up my forehead acne. I'm not sure if it was the chemicals in the shampoo irritating my skin or just too much oil, but it has helped.

3. I've been trying to temporary eliminate dairy and nightshades from my diet to see if it helps. Since I've been traveling frequently, attending weddings, etc, I've had to eat some less than ideal food. I haven't been able to actually determine if dairy and nightshades help cause my acne, but I almost always get a small amount of acne a couple days after eating out.

4. Trying to increase the amount of probiotic foods in my diet. Many paleo people say acne is a reflection of gut health. I'm starting to make my own pickles and kefir to see if it has any effect.

Have you been eating eggs and dairy? These can cause issues for some people, particarly skin issues. I assume these were not included in your diet beforehand, being a vegan.

Don't eat too many nuts, many are high in omega-6. And make sure the fish oil you are consuming is good quality from an origin/brand of reputation, not oxidized or rancid.

Acne is likely indicative of leaky gut; that is, damage you have done to your digestive system while eating grains.

Focus on a nourishing, grain free, dairy free, legume free, diet for a period - it will eventually heal. It took me an entire year to completely heal my gut, and that was after growing up SAD, vegetarian for a couple of years, and raw vegan for a couple of years. Your healing period may be longer given how long you were dependent on toxic energy sources.

Realigning your gut flora will also be a big part of this healing process; I'd recommend something like a live kefir, homemade kombucha, or good quality yogurt; pro-biotic pills alone were never enough to really help me start building a positive gut population.

Food wise: personally, I focused on coconut oil to begin with and let my paleo unfold from there; these days I eat a lot of salmon, shrimp, grass fed beef, lamb, broccoli, brussel sprouts, asparagus, and kale - all slathered in coconut, palm, bacon, tallow, ghee, goat butter, pastured butter, and avocado. Try to stay as close to 100% gluten free as you can - wheat really punches holes in the gut like nothing else.

For me personally, nuts and seeds as well as fruits tend to cause breakouts. As long as I avoid these, my skin stays blemish free. I think everyone is different in how they react to different foods because I've also noticed that cod liver oil, butter oil, and probiotics make my skin "glow" without any need for makeup or special cleansing regimens (and none of these cause pimples for me).

I'm a big fan of vinegar as an anti-fungal. I've been using it for years to keep my dandruff in check. Everyone has these critters living in their scalp but people with dandruff have a low tolerance for them. So while acne is inflammatory, it is also contributed to by skin bacteria (propionibacterium acnes). Vinegar is anti-bacterial as well as anti-fungal so you might want to give it a shot. And as others have already mentioned, you probably want to rethink the nuts.