Beverly

My 5 month old German Shepherd Dog puppy continues to have generalized itching. We have tried Raw, Fromms, California Natural Grain Free Venison Formula, which he is on now. It has a short list of ingredients to limit potential allergens. His vet continues to tell us he can find nothing on his skin to attribute to the problem. No fleas, mites, etc. No redness. No fur loss (yet). My poor baby looks miserable, and other than the itching, is absolutely perfect. What should I try next? I have another call in to the vet. I have a feeling they're going to recommend Benedryl, but that treats the symptoms, not the cause. HELP!