Suggest Treatment For Sharp Pain In Knee After Walking

Hi on the 2nd February 2014 I was going about my day doing nothing strenuous .... helping a friend look for flats went for a meal and then the cinema. On standing to leave the cinema I had this horrific pain in my right knee on the right side and my friend had to help me to the car. Had an xray at A &E and they said it was muscle and tendon injury and sent me on my way! I am still in agony .... I am taking co codamal for the pain and diclofenac but no advice on what to do? can you help?