I'm 20 years old and live a relatively active lifestyle. I've never had any problems with my knee (and fortunate enough to not have any major health issues). Anyways, around Friday, my left knee started to hurt. When I tried bending my knees, squatting, walking up and down stairs (primarily down), I feel this pain at the top of the left knee. When I flex it, I can feel something (not sure how to describe it). Any suggestions on what it is?
Also, note: it cracks when I bend it, but it doesn't hurt.