Have you tried a low FODMAP diet
? It may help. I have a LOT of food sensitivities, and that was one of the first places to start. I avoid coffee, sugar, gluten, greasy or fried foods, too much dairy or meat, and too many beans and cruciferous vegetables.
My stomach has never felt better. I started with eliminating coffee and gluten (and I've avoided sugar and greasy foods for 20 years).
I ended up adding some of the low FODMAP foods that didn't bother me like onions and tomatoes.