M.S.
I had a cocker with allergies. You can give them generic benadryl and hide the pill in a treat, which was recommended by our vet in Tucson. About a week of that helped my cocker's allergies clear considerably (enough to make the sores mostly heal), although they didn't go away completely. You can probably research giving dogs antihistamines on the internet. Try to remove likely allergens from the home, vaccuum frequently but put the dog somewhere else while you do it, etc.