Hi, So Overtime This Bump On The Upper Part Of

Hi, so overtime this bump on the upper part of my belly button has been getting swollen and it is getting much worse. It is now purple colored. I thought it was from my belly piercing but it in fact doesn't even involve that. One of my friends had told me hers got infected from sperm getting in her belly button after sex. Could that cause this, and if so, what can I do to treat it?