Whats wrong with my knee?

I lost a ski after a little 10ft air and tried to stop with my left leg dowhill. My knee got rotated uphill and it was just about 50ft of cartwheeling after that. After I was done rolling I noticed a sharp pairn in the back left side of my knee wrapping around to the front. I laid down the about 10 minutes then proceeding to hike back up, get my skis, and ski the rest of the day. I thought i had just twisted it, no big deal. The day after, till now a week later I have not been able to lock out my knee or make quick movements without being in pain. Stairs are also a killer on the knee, but in a different way. I'm heading to the doc on monday.Just want to be prepared for what I'm about to hear if you guys have a clue.