What Causes Pain Behind Knee And Muscle Tightness After Stopping Exercise?

hi i am 45 yrs obese female earlier this yr i started excising mainly treadmill i stopped for a little while now i am having severe pains behind my right knee the muscle is really tight and most painful when i am sitting or climbing stairs i am rubbing with voltaren and also tking those tablets but the pain is not going away. another thing yesterday i stepped into the bus and i felt like the mucsle behind my knee snapped and now i can only limp not walk normally please help is this tendonitis hamstring or what... Felicity