I had a small mole on my shoulder for what seems to be my entire life, but these past few days it's grown and gotten darker. It's not HUGE but it is bigger and it kind of bleeds a little bit, there also seems to be blood underneath it, what could it be and is it serious? I wear a lot of tank tops so I'm not sure if it just got irritated, or maybe infected, I'm afraid it could be something like cancer...