I'm really thinking it's Wheat, Wheat, and Wheat! I really do. Since the treats were fed along side the foods - and they coincided with the vomiting - and they're NOT in the other foods (nor in Newmans) - I'm thinking wheat. I think if you discontinue the wheat, you *may* be able to feed one of the other foods besides Newmans - just as long as there is no wheat. That'll be an ingredient to always look for going forward, but good you found that out!