Any one know what this is??

Hello, on 06-09 I got a red rash under my breast. After a couple of days it now seems to be flaking. Any idea what it could be and what I can do to make it go away? It’s only on one side and it goes all the way to the middle of both of my breasts. It’s not as bad in the center and it definitely only appears to be on that same side.

Should I try to see a Dr?? Or is it not a big deal? Any thoughts/advice are much appreciated. Thank you.