Hi, I'm 15 years old & my left knee hurts me just about ALL the time. It hurts the worst after I do something active, but even just walking for about 20-30 minutes it hurts me. I use to cheerlead when I was 13 & I never had a problem with it. & a couple of months ago, maybe about 3 or 4 actually, it swelled up real bad for no reason it was later on that night but earlier that day I was really active, running & stuff. Ever since then my knee has just been a dang pain.! I have been to the doctor because one morning I woke up & couldn't even walk. He gave me some anti inflammatory medicine, but it didn't help. I still had pains WHILE on the medicine. I went back & he gave me more of the same medicine just a longer dose. I haven't went back because he'll more & likely keep giving me that medicine. He thinks that my ligaments/tendons or whatever haven't caught up to my bones yet. If you can confirm this, or thing it's something different please let me know, cause I hate just not being able to run around & having a consequence. ):