Red and itchy under breast

This has been going on for a couple of weeks. I thought maybe it was just from my bra rubbing me wrong but now I'm not sure. The area is itchy and I get a lot of dead skin (I think?) that comes off when I rub it. It smells bad too,

as gross as that makes me feel.

Anybody have something similar happen? I just don't know what's going on here.