your symptons sound similar to ones i had. I had varios doctors tell me differnt things, and in the end went to an oestopath. A kind of healer but not so wacky. She told me the muscles in my leg had varios injuries it had never recoverd from. My problem was when i put weight on the knee when it was bent, it felt as if it was going to give way. It felt weak. Give this a try:
1.) Do some streching every night before you go to bed, hamstrings, quads and groin.
2.) Avoid running and any kind of sports for a month and see how it goes
The problem i had didnt get better untill i took 7-8 months out of doing anything to do with fitness, and after that i joined a gym to tone and build up the muscles in my leg. Since joining the gym it has helped to no end, my legs feel stronger. anyway hope you havnt got what i had, it can be rather dishearnting at times. espically for someone young who jus wants to play footy but cant
