Im trying to diagnose a grumbling knee that has developed recently. I have a slight pain when getting up from a chair just below my left patellar. Its kind of a sharp pain that i think might be early patellar tendonitis. However, i've managed 27 miles this week including the Surrey slog and it hasnt swollen up or got any worse......Any tips to strengthen the tendon or more accurately diagnose the problem gratefully recieved!!