Last winter I developed an itchy rash on my lower back. I treated it with hydrocortozone (.5%). The itching is gone but I am left with a large dark blotch which isn't going away even after using Neostrata lightening cream. This winter I have that same rash on upper arm and it has spread to my back. It looks like a cluster of small dry pimples moving onto my back in straight line. When I scratch it, it leaves dark blotches that just won't go away.