I just went to take a shower and felt a lump in my armpit!! It's about the size of a marble, maybe a little smaller, and it's very hard. The thing is is it's red, so you can visibly see it. I tried to take a close look at it, and it looks like maybe there's a small raised brown spot on it. I am thinking maybe it's an ingrown hair follicle or a cyst, but it's deeper than just the surface, and it scares me that it's so big and hard. It's a little sore to the touch, but not necessarily painful. Any opinions? It seemed to come out of nowhere? Should I call the doctor or try heat compresses? Since it's red, that's probably good, right? I'm trying not to think that this is from metastatic breast cancer or something!!!! HELP PLEASE!!!