I won't be much help here but my sisters Scotty has TERRIBLE allergies and itching...the poor baby is miserable all the time. Her vet put her dog on an all vegetable dog food but I can't remember the name of it. He is also on meds and steroid shots and after extensive test and different meds and visits to the vet they still don't know exactly what is causing it. Sorry
I'll try and remember to ask her the name of the dog food next time I talked to her! Hopefully someone else will have a better response.