ok, i'm 16, and recently i found 3 bumps in my armpit, two on my right side and one so far on my left side, the size is smaller than a pea, it's semi-hard and is able to move around. It doesn't hurt, but i'm really afriad it's cancer or something. Also, when i lift my arms, it's kinda visible, only if you look closely, could this be cancer? should i go visit a doctor?