Wash the area with a mild soap or doggy shampoo. Dry it thoroughly. Apply a bit of neosporin and cover it... putting a t-shirt on might be the easiest. You need to keep her from scrathiching the spot raw. Also, I would add some extra oils to the diet. A tablespoon of olive, sunflower, or flaxseed oil daily is great for the skin. If it still fails to clear up, then it is possible there is a bacterial infection or even fungal and she might need extra meds... have her checked.