It does sound like psoriasis- which I was also diagnosed with. It is really tough to deal with, because as I said before, it could be related to soooo many environmental factors. A word of caution if you visit the dermatologist, of course, they will put you on topical creams and medicated shampoos. None of which ever worked for me. I also got a shot of some steroid....and it was the only thing that helped get it under control initially. I hate to admit it, but that shot helped every time.
However, not something I wanted to stay on for life. Thus all of the adjustments mentioned previously. Once I got it under control with the shot, then I was able to continue trying all of the natural stuff. It sounds like you are doing alot of the right stuff already. But you may be more stressed out than you realize. I don't necessarily feel stressed when I have my big breakouts either. But the last one occurred last Nov.......holidays approaching, work gets really busy for me, we lost our 13 year old dog, some financial issues.....on top of having a 4 yr old and a 2 yr old. I didn't feel stressed, but my body told me otherwise and I had a big flareup. Back to the dermatologist and a shot. The good news is, since then it is completely gone (or in remission) and I am continuing with the fish oil. Again, I cannot stress enough megadosing the fish oil. I know you said you used to take fish oil, but I'm talking between 6 & 10 grams a day!!! That's alot of fish oil!!!
The shampoo link posted by SummerLover looks fun. I think I would like to try it. But I would suggest for you a very boring kind of shampoo & conditioner. I use JASON fragrance free. It is sooooo boring. No fun stuff at all. Although, sounds like what you are doing now would be mild enough. But, who knows, everything is worth a try if you are desperate enough. I know that feeling.
Also, althara gave good advice as far as an offending food. You may have a great diet, but maybe something is bothering you like dairy and/or gluten. Or of all things, pork. Pork is really not good for me.
And finally, just wanted to suggest some books (check your library) that may be helpful. I personally did not have to go to these lengths, but I was prepared to.http://www.amazon.com/dp/0895299178/...pf_rd_i=507846http://www.amazon.com/Healing-Psoria.../dp/0962884707
Good luck!! I so wish I could help you more cuz I know how frustrating it is!!