What you are describing could be mange. There are 2 different types of mange, sarcoptic and demodectic. Both are caused by mites that live in or on the skin. Sarcoptic mange is very itchy, and usually starts on the tips of the ears
and the elbows, and is highly contagious. Sarcoptic mange is relatively easy to treat.
is not itchy, and often starts on the face, around the eyes
and over the body, and is not contagious. It is much more difficult to treat, usually requiring weeks or even months of medication or topical treatments. This type of mange usually signals that your pet has some type of underlying health problem, such as an immune system that does not function correctly. Pets with demodectic mange should not be bred, because the underlying health problem is genetic.
These conditions are diagnosed by a veterinarian by doing a skin scraping and examining the material under a microscope.
However, there are many other skin conditions that can appear the way you have described. I would recommend that you take your dog to a veterinarian to get the skin examined so you can get treatment started. I hope this information helps!