You do not have a tendon problem,you have a muscle problem,as the force which is causing inflammation is not adequately absorbed by the primary structures meant to absorb it,read :muscles. So any supplement addressing the tendon problem will address only and always the symptom,while doing nothing to address the origin of the problem,which lays in the lack of communication between appropriate muscles meant to manage forces around your knee joint and stabilize it.
Here follow some videos of exercises which may help you by restoring and increasing appropriate communication of which above. I would suggest you do take a rest from all training which elicits pain level above low,and concentrate on performing daily those exercises which you get the most immediate benefit from,and resuming regular training once painless. Remember adaptation to any training will always be severely restricted by any pain you may endure through multiple inhibitory reflexes which will limit the quality and quantity of active tissues (the only ones exposed and hence responsive to the stimuli).
http://www.youtube.com/user/ARPWAVE1#p/u/57/pQEREVenilY
http://www.youtube.com/user/ARPWAVE1#p/u/55/_sM8err9XUs
http://www.youtube.com/user/ARPWAVE1#p/u/56/eifzv9VwR9w
http://www.youtube.com/user/ARPWAVE1#p/u/44/3G31Vi9GwJI
http://www.youtube.com/user/ARPWAVE1#p/u/45/AdiktY4NScg
http://www.youtube.com/user/ARPWAVE1#p/u/46/DgvzTlHw5pY
http://www.youtube.com/user/ARPWAVE1#p/u/15/RLUquVSqpH8
http://www.youtube.com/user/ARPWAVE1#p/u/14/yGFDUqHS798