Obviously, this question's going to be a little gross, so don't judge me for it :P
So I was at school yesterday (sophomore) in the bathroom, and it felt like my underarm was sore. I felt this little bump. So yes, it appeared randomly. This was during lunch, so I waited a few hours until I got home to investigate the world wide web. I got the results it could be breast cancer, clogged lymph node, breast cancer, ingrown hair, breast cancer, a boil, and... oh, yeah, breast cancer. All of the results sound semi-similar, so I'm having trouble deciphering.
It showed up randomly yesterday.
It hurts when I squeeze it or put my arm down.
Yesterday, I squeezed it, and a little pus or what or whatever came out (gross, yucky).
It's basically the size of a jelly bean.
I feel may have gotten a bit bigger since yesterday, and nothing's coming out if I squeeze it.
I placed a warm, wet washcloth underneath it yesterday, but then I fell asleep, and I feel it didn't work.