I'm 16 years old now and i have a very bad knee pain. Makes a cracking sound whe!

I'm 16 years old now and i have a very bad knee pain. Makes a cracking sound when knee is bent .?

Last year on the year 2006 i was very active in sports. At about the month of august i discovered that my knee makes cracking sounds and hurts when its bent. Sometimes it feels like there a glass under my skin and my leg will be weak for awhile. I tried acupuncture for about 3 months and it didnt work. I've not played any sports for about year now. My knee cap is always cold dont know whats wrong with it.The simptoms are in the both of my knees which worries me alot. Can anyone tell me whats the problem with me? please...

Sounds like patellofemoral syndrome, which is fairly common for kids your age and with your activity level. Basically your knee cap is not tracking properly and this irritates the tissue around and underneath your knee cap. I would recommend you go see a doctor to have a look at your knees and then try some physical therapy to strengthen your hip/butt muscles to take the stress off of your knees.