my black lab chews at his legs until the fur is gone and underneath he has little red bumps. the skin is also dry and scaley looking. I've also noticed that he has little sore-like places around his neck area. he has crustiness from his nose. is this an allergy? what do I do?

Optional Information:
Age: 3; Male; Breed: black lab

Already Tried:
oatmeal bath, antiseptic for hot spots