Disease Hair Inside The Vigina Dog Has Skin Problem With Hair Loss?

Dog has skin problem with hair loss? - disease hair inside the vigina

My dog has a skin on the back just before the tail, and is now in the tail, and hopes that the form in the legs. The skin becomes red and brown crusts and swelling / bumps. The hair becomes thinner in these areas and where it is again grown short and thick. It is very itchy and bites into it and rolled back down. This happened during the same period last year went. But as it is worse this time and go to the vet, ask what is the disease or parasite that?