Given that your dog isn't very old, I would try to find out what he's allergic to. You can do a elimination diet and add one ingredient at at time. Not balanced is OK for a short period of time or you can buy the veterinary formula for a short time.

 I'd rather see such a young dog getting a variety of protien and carb sources because they can become allergic to frequently fed foods as they age. I had a dog that became allergic to shellfish based glucosimine and it caused really severe problems.