Hi, thanks for writing to HCM.
Looking at your description and the syptoms, I am of the opinion that you might be having either problem in the articular surface of the patella
(knee cap) or it could be due to catching of infrapatellar fat pad within the joint (Hoffa's disease).
* Rest to the knee joint
* Intermittant ice compression
* ocassional anagesic medications
I suggest you to meet an orthosurgeon if symptoms persist. Hope this helps