I Have A Mark On The Top Of My Right

I have a mark on the top of my right foot. It's similar to a burn in that it's red, slightly raised and the skin over the area feels a little dry and separate from the layers of skin beneath it. But it doesn't hurt or itch or anything like that, no discomfort at all. The area is actually significantly less sensitive than the same area on my other foot, so it's sort of numb. I haven't hurt it, or rubbed it or anything of the like to my knowledge, it's appeared somewhat randomly. I was just wondering what it could be.