What Is The Treatment For Red Patches On The Arms?

I have 3/4 raised red blotches grouped on my right side, round about where my ribs end. They're different sizes, the largest being about 1cm in diameter. The inflamation is larger than the raised element. They're sensitive to touch but not exactly sore. I don't think they've been there longer than a week-if that. At first I wasn't too bothered but I'm getting more concerned now.