I have a painful bump on my butt, it was peeling and was leaking, what's wrong?

Cyst or abscess. This is most likely a cyst or abscess and may need to be drained. Using warm compresses may help it come to the surface, but i still recommend seeing your doctor as drainage and/or antibiotics may be necessary..
Pilonidal sinus. This is hair shaft abnormality you were born with that developed into inflammed tract. You need to see physician to drain, culture. The drainage will remove the pus and allow it to quiet down. Once quiet, it can be removed surgically. For permanent removal the entire tract needs to be removed.