Hi, I am a 21 year old male, and have discovered a small lump (or circular bump? Don't know what to call this...) on my chest. It is about 1 cm in diameter, a little discolored (on the dark purple side) and it feels very solid to the touch. It does not hurt or bother me when I leave it alone, but one time I accidentally popped it and a lot of white pus followed by blood came out. The bleeding stopped, but the lump is still hard, and still there. Would you have any idea what this is? Or how to treat it?