Is THAT what it is?? The mare I ride had something like that when she was 4. Puffed up bigger than that, and was warm for a couple days, but never lame or sensitive to touch. I gave her a little time off, because I was worried about it even though she didn't seem lame. It shrunk down a little, and we went back to work. But even now, 4 years later, you can still see it. It's about the size of the one on your horse. I don't think it'll ever go away completely, and is just a blemish we're going to have to live with. Yours is so small though that it might go away/be impossible to see.