I would look for a simple formula... while I think RX foods are great and have their place and help a lot of dogs, I don't think it should be the immediate answer for an upset tummy. Most of the time, they're to be used temporarily.
Check out Canine Caviar Special Needs formula. California Natural also has some simple formulas. Precise also has a lamb & rice simple formula, I believe!
Food allergies are actually very uncommon, they only account for about 10% of dog allergies.
Good luck
