This past yr my dog all of a sudden started doing the same thing. My daughter is a groomer and said she had a yeast infection; down below and in her ears. I took her to the vet and at first he didn't think that's what she had but, yes it was. Plus all of a sudden she's sensitive to the fleas to the point that her skin turns red; like inflammed. She's always been on flea prevention but with some dogs it only takes on flea to cause this. I changed flea meds to internal once a month and she took some antibiotics. She's alot better and her fur has mostly grown back. My large dog we give vitamins too and they help his skin along with his joints. Plus when his skin is really dry we put Skin So Soft on it and that helps him.