Not Medical Advice: It may be a condition called prepatellar bursitis, the inflammation of a small sac of fluid located in front of the kneecap.
Prepatellar bursitis causes pain and swelling in the area in front of the kneecap and just below. It may be very hard to kneel down and put the knee on the floor because of the tenderness and swelling. If the condition has been present for some time, small lumps may be felt underneath the skin over the kneecap.
Prepatellar bursitis that is caused by an injury, as in your case, will usually go away on its own. The body will absorb the blood in the bursa over several weeks, and the bursa should return to normal. Learn more about diagnosis and treatment.
As the largest joint in your body, the knee takes on its fair share of impact. Not surprisingly, knee pain is a common complaint among people of all ages. Check out some tips for preventing knee pain at Rush University Medical Center.