I Have A Purplish Pimple On My Breast. It Started

I have a purplish pimple on my breast. it started about a week or two ago as a tiny little hard pimple that didn't hurt. now, it looks purple and it's red around it. when i tried to pop it, it only had a little blood come out of it. it's not hard now. like it's dissipating. I do have large breasts.