How old are you? Are you a woman? Are you fat? (sorry for being personal) If you are middle aged, a bit on the portly side, and especially if you are of the fairer sex, it may be a paraumbilical hernia. Bit hard to tell without seeing it though. These often need to be operated on as they can eventually cause problems (like bowel obstructions). Bet you can't guess what I recommend you do............
