I am 20 years old and have a two year old son. I have a petite body build and have not gained much weight lately. I got one lone stretch mark on my right breast while pregnant and it hasn t bothered me until recently. It is extremely painful and seems to be getting larger; it is hollow-like and looks bruised. My right breast hurts pretty much all the time but every now and then, I will get a sharp stabbing pain where the stretch mark is, sometimes it s so bad I almost cry and can t breathe. When I think cancer, I think of a tumor, so I have no clue what this hollow spot could be!! Please help..