Hurt my left knee playing soccer a couple years back and it bothers me sometimes. i didn't break it or anything. i don't think. i can move it.

See a provider: If your knee hurts so bad you can't move it you should see a medical provider right away to be evaluated. At the age of 16, with a knee that you injured a few years ago, there could be several things causing pain. You will need an x-Ray to look at your knee bones and possibly an MRI to assess for cartilage, ligament and/or tendon injuries.