Boy oh boy, I second the dairy! I have been on an elimination diet for 21 days and am slowly adding items back in to my diet and recording how I feel. I eliminated gluten, soy, dairy, corn, sugar, peanuts (and one more thing that I can't think of right now). When I have allowed myself to have something off the list, my main culprits that upset my tummy are dairy, and surprisingly, the sugar. I can tell when I've had gluten, but it doesn't upset my stomach nearly as much as the dairy and the sugar do. Also, my skin has never looked better and I attribute that to going dairy-free. OP, I would definitely try eliminating dairy if you are having the stomach issues.