I'm not a doctor either, but I can share a knee pain experience I had. I had tremendous pain in my right knee exacerbated from wearing spikes on an indoor track. Doing an easy run on the weekend with a teammate, the pain in my right knee was so bad I had to stop, walk, or limp, the rest of the way home with about 2 miles to go. Finally I got home but found that I couldn't bend my right leg to walk up a few flights of stairs.
I was out for a very long time and depressed after just running a double of 4:22 for 1600 and 1:57 for 800 indoors a couple days earlier. All that work down the drain.
Anyway, my coach and school PT determined that my IT band was too tight and that my quad was too weak. To stretch my right IT band I would cross my legs with my *right* leg behind my left, then lean my upper body sideways to my *left* side while keeping my legs perpendicular to the ground. I'd use a wall, tree, or something for support so not to fall over while leaning. For my quad, in a sitting position I would extend my leg straight infront of me and simply raise and lower it a few inches. I did repeats of this every couple of days. Those helped my knee track properly and I never had the pains to the same degree again. Problems lingered, but not nearly as severe as before. Also did a lot of icing in the ice tubs after runs.
I had been to a bunch of doctors in my day for leg/knee problems. Two were good and one was a complete ass - he was very cocky but didn't know diddly-squat, didn't observe me walk or run, and spent about 2 minutes "evaluating" me. This guy's "diagnosis" of the problem was about as far off mark as it could possibly be as were his assumptions of my abilities. I overheard him say to an assistant in another room that my knee pains were a result of me being only some "Sunday jogger" and that I was "in over my head" and that I wasn't "able to handle such a rigorous running program." Ha ha! What a moron. He didn't even recommend any stretching, strengthening excercises, or icing. So, make sure you get a second or third opinion from a doctor or physical therapist who knows what they're talking about.