I Had A Bike Accident And Fell Hard On My

I had a bike accident and fell hard on my right buttock and hip. It swelled immediately and over the next few days became a huge bruise and massive swelling. After one month there is still a swelling about the size of a tennis ball. It has become very painful, shooting, stabbing sharp pain that is on and off. there is hard flesh around the out side of the swelling and seemingly a soft center... whats going on?