Hi, i am female 31yrs old, i recently felt a small pimple like lump under my left breast on top of ribcage so while I was in hot shower I try to squeeze it and like a whitehead a little nodule like with small hair came out. So I thought that was it. The next few days I had been monitoring it and a small lump has appeared it hurts now and again but certain times just a small lump what can this be?