Can someone please give me an idea if this is rain rot? It is on her butt and withers, but nowhere else. It doesn't appear to be itchy, and isnt leaving her bald or with sores. She has hair that has grown in under it. If I pick at it, it does come out in clumps. I thought at first she was shedding again, but I have never heard of a horse that sheds twice in one year. What do you guys think?