When I was in college, it happened to me. I was on a summer job, about 8 hours from home and had a lump the size of an egg under my arm. I found a doctor (OB/GYN) who said "It needs to come out", so I called my mom, who got me set with a surgeon at home, quit my job early, went home, and heard the surgeon say that it was a lymph node and we needed to leave it alone and watch. He suggested "cat scratch fever" too. It eventually went down, without surgery, and I have had no further problems. I would only tell you that you shouldn't take these things lightly, have it checked by a doctor and maybe two doctors to be sure.

Good luck!

Logan