I fell on some metal stairs about 3 weeks ago, and I cut and bruised one knee and got a bump and bruise on the other one. The bruises are almost gone but on the knee I got the bump, right on the top of the bone, has been feeling really stiff. Sitting for long periods of times make it painful to straighten my leg and then to walk on. I thought it might be a bigger injury cause normally a bruise wouldn't affect my walking..... any thoughts? I don't want to go to the doctor if it really isn't anything though.