You may want to try organic dog food. Nature's domain is good, either the red or green bag. It's cheaper at Costco. Lots of dogs with hot spots and itching from allergies is from all of the chemicals and GMO's in traditional dog food.
so my dog has been having a chronic skin infection for about the past 2 years now, antibiotics would make it go away but it would always come back. Most recently i took him to the dog dermatologist, he was placed on this soy dog food thats quite expensive, and he has gotten much better. So supposedly he has a food allergy, possibly to beef or chicken or whatever. I agree with the food allergy, but have a hard time believing a dog is allergic to meat. I am thinking its more along the lines of whats in the dog food, or how the dog food is made, or any number of other ingredients.