I'm 20 yrs old and have a painful bump between my breasts. I keep popping it and a ton of puss and blood comes out but it keeps coming back. Ideas?

Abscess. Go to you doctor, and get the pus drained completely and antibiotics to clear the infection to cure. Youv will also need at least wound (pus) culture. The depth of the wound and bone involvement need to be checked as the length of antibiotics will be longer if bone or joint involved. Be Well.
Sebaceous cyst. Since your treatment hasn't cured it -see your doc. You may need minor surgical removal of the cyst.