It sounds to me like some kind of skin problem, most likely an allergy. As a groomer, I am around a lot of dogs with skin problems that need special medicated shampoo and care, and from what you're saying, it sounds like an allergy, either food or skin-related I can't say. I would take your dog to the vet, they can do a test on the skin to make sure it isn't something else like a skin fungus (which it could also be) or something more serious. The most common thing I see with those kind of symptoms, though, is allergies. That type of dog, too, with the very, very short coat seems to have sensitive skin. A good example is the English Bulldog, as well as Italian Greyhounds and Bull Terriers. Hope I helped