My 17-year old son has had what kind of looks like a large zit on his leg, only it is black. It was also painful to touch or lay on. Sometimes he gets puss out of it. He won t try to pop it because it is so painful. He hasn t let me get a very close look at it, and I thought that maybe he had an ingrown hair. Today he decided to pop it, and he got out a small, hard object that kind of looks like a small bead - a little smaller than a BB. It has a partial opening like the hole in the bead, but it doesn t go all the way through. The area on his leg is still black. But he still won t let me get a very close look at it. This seems really weird. Any idea on what it could be?