What is this and how do I treat it?

I gave birth to my 2nd child almost 2 weeks ago and have been exclusively pumping the whole time. In the last day or two I’ve developed a rash of some sort on the top of my breasts, I think mainly from massaging that area with my hands while pumping to help empty better. As you can see from the picture, it’s fairly red, and also itches. Suggestions for what I can do to help clear it up? I recall having the same problem on and off with my first, but can’t remember what it is or how to treat.