Discoloration now peeling?

I was put on some medicatino (tegretol) and about a month later developed a rash on the back of my arm and discoloration on my chest area. Its like a baby bib, just skips over the inner part of my chest, and hits the same area of my arm where the rash was. I find it noticeable but others can barely see it. But now its starting to peel, and im not really sure if its a good thing or bad thing...will this ever go away?