You should go see a food allergist and they will test your body and give you a list of foods you're intolerant of. It should give you an idea of where to start your elimination diet (the doctor should be able to give you further advice on it as well). My friends did it (mostly out of curiosity) and the list was like 4 pages long, so be prepared! They rate the intolerance from greatest to least, but most of the culprits are right at the top - refined sugars, processed wheats, alcohol, etc. There were also strange things on there, like pickles, beets, kale, and the such...things that you might not think of as culprits, but they ranked fairly high on the intolerance scale. Both of them also discovered that gluten was pretty high on the list as well, even though they weren't full-blown celiac.