Well, without a physical evaluation and probably a few tests, it would be difficult to point out the
cause of your discomfort. I would suggest an evaluation by an orthopedician to look for injuries in and around the knee
joint like fractures, ligament/ tendon
tears etc. Meanwhile I would advise keeping the knee
partially immobilized. You may use a crepe bandage for the
same. Alternate hot fomentation and ice-packs with some tylenol/ NSAIDS may provide some relief as well.