I recently got over mono about a month ago. However, as I was recovering I got a seeming rash on my back. It's been there for over a month now. It seems to be spreading also, slowly though. When it gets hot or after a shower, it gets redder, but when I'm not hot or anything it's a very light pink, hardly noticeable. Sometimes it's itchy, but most of the time it's not.

I am not taking any medications at all.

What is this???