I just found a lump yesterday under my left armpit. I noticed it because this spot was very sore to the touch. I have had pains in my chest lately and have been taking a vitamin B12 injection that has a fat burner Lipovite. I thought I was having a heart attack last week and the cardiologist said it was pleurosy. I am worried about this lump. I am 42 and about three months ago I did have to treat some lumps in the pubic area with antibiotics. I have a couple of fatty tumors also on my left leg.