I Have An Infected Cartledge But It's A Small Bump

I have an infected cartledge but it's a small bump on the back of the ear. I had a hoop, and I got it pierced about a year ago. I took the hoop out and I put in a stud that I bought at belks. Well I had it in for a couple days, and it started getting infected. I took it out and tried to get the hoop back in but it wouldn't work. The back of my cartledge started bleeding this morning. Please tell me what I should do to help it.