My kneecap hurts after falling. What is treatment?

R.I.C.E. Rest, ice, compression and elevation are the basic things for trauma. Homeopathic arnica can really help as can homeopathic bryonia. Keeping leg elevated helps a lot to keep blood circulating and decreasing discomfort. If pain continues or you have significant swelling you will need to be evaluated. You may find that traumeel also helps.