I have to agree, that at this point I would be going to a specialist to get a U/S - why wait, why chance something
and your right that he can't be on those meds for long without side effects popping up on a young pup
Glad you cleared up about the Pedigree not being your first choice, but honestly IAMS is pretty bad too
Some better choices would be:
Canidae
Merrick
Natural Balance
Nature's Variety
Solid Gold
California Natural