I have a red rash on my arm in the shape of a ring. The exterior is raised and the interior is white. In fact I first noticed it because it is the one area of my arm that did not tan when I was out in the sun (with spf nonetheless) in the middle of July. It s almost 2 months now and seems to be getting worse. When I moisturize it, it seems to go down, but only temporarily. What is it, what caused it, and how can I get rid of it? I think it s a ring worm , but not sure.