Welcome!
Unfortunately trial and error is the only thing that will help you the most. We could all tell you what we can or can't eat, but you may be very different. Some of the most common things I have heard are dairy products, greasy fried foods, spicy foods, red meats, onions, lettuce for some. Some others have tried gluten free diets or SCD diets.
My worst food is beef...always gives me terrible cramping. I can eat cheeses but not milk. Onions don't bother me and lettuce is so, so. Anything high fiber upsets my system. I avoid greasy fried foods (per dr. instructions and sheer fear). I also avoid soda and coffee...oh how I miss coffee. All in all the less I am flaring the more I can eat. When flaring I stick to an almost liquid diet (Ensure shakes and maybe some crackers) as that is all I can manage to eat.
Hope this info helps. I would keep a food diary so you can see what foods seem to trigger bad responses. Remember it could be things that never bothered you before...like beef with me, I use to eat it nearly every day and now I can't have it ever without paying the price.