I have bad breast acne. A couple of months ago I developed a pimple under the skin on my breast. It started off small and was kind of dark in color like a blackhead but as time went on it got bigger. I tried squeezing it but nothing came out so I left alone. It eventually went away but now I have this large dark area on my breast and a scar that still looks like a blackhead. Is this normal? Should I be worried?