hi there, you might have twisted the joint with injury
to the ligaments. Get an x-ray done to rule out any fractures
. If none then the best treatment would be to give hot fomentation, elevated position, crape bandage and anti inflammatory pills for a week or so or till the tenderness comes down. Usually ligaments take a long time to repair and it should be given ample time and rest. Do not massage
or exercise the joint and let it heal on its own. Put as little pressure or weight on the joint as possible. Take care.