Have you ever had a RAST test or scartch test for allergies? When people think of food allergies they generally think of the hives, swelling, throat closing, etc.. However, sometimes it can be stomach issues as well. I would find an allergest or ask one of your doctors to throw a RAST test which is just a blood draw, for maybe start with the top 8 allergens (wheat, egg, dairy, soy, peanut, treenuts, fish, and shellfish) then go from there. I hope you find some answers!! Both my kids have food allergies, so I have learned alot over the last two years about food allergies.