Hi over 3 weeks ago I injured my left knee at a Tough Mudder event going down a slip 'n slide type obstacle, with my knee bent over 90 degrees came to a sudden stop, now I have pain on outside of the knee, kneecap, clicking on that side and back of, also I can't bend the knee more than a 90, I can feel grinding sometimes under the kneecap, my knee is also swollen. My doctor says it is a sprain, I haven't had an MRI, ultrasound or xray. I do ice it a few a day for approx. 15 minutes at a time.