If the cause of UC was one thing then it would have been cured years ago. I think that it is caused from different things although there probably has to be some sort of genetic predisposition. A flare is probably initiated by some sort of imbalance in the stomach's bacterial fauna which might be caused by a course of antibiotics or stress (don't underestimate the impact that stress can have on your UC. I recall that stress chances the acidic balance of your stomach and might therefore affect your bacterial balances). Once the flare is underway then it can be exacerbated by foods which don't agree with you. Again this might be causing additional bacterial imbalances in your stomach.
I think you need to find out what disagrees with you foodwise and what helps you treatment wise. Try different diets and treatments but don't stick with them too long if they aren't working. Its costly and wastes time. See as many health professionals as you can (afford) but remember that they aren't god and if they had a patented cure for UC then we would all know about
Good luck with your fight. Hope you find your answer.
49yo single dad
mesalazine 1.5g, prednisolone 15mg
tried infliximab (remicade), humira, salofalk (5-asa enema), entocort, Azathioprine, steroid emenas, abadacept