Felicia, a bump in your armpit could be all kinds of different things. You don't say how old you are, but I'm assuming you're younger, since your mom is around. Breast cancer usually occurs in older women; it's incredibly, INCREDIBLY rare in women under 20, and VERY rare in women under 30. Most women who get breast cancer are in their 50s at least, and most likely over 60. That said, congrats for being aware of any changes around your breast, and that includes your armpit; that's the way we help protect ourselves from cancer. Since you seem quite worried, why not have a doctor look at it? That would set your mind at ease, and you could find out exactly what it is. OK? Good luck - PJH