I hit my knuckle about 3 weeks ago on a metal bin that I was hammering at full force. It was immediately swollen, which I assume is normal after an injury like that. My problem is, that 3 weeks later its still just as swollen and, almost at random it will flare up and hurt again at what I would say is a 5 or 6 in pain for a couple of hours. When I lay it flat it is almost as if its just the skin flap has gotten bigger or something, and its my pointer finger, right hand , middle knuckle. What could be the cause of this?