Skiing Fall... Can't support weight on knee.?!

Tonight I was taking a turn on the ski hill and my knee popped. I fell backwards and felt an intense pain for a few minutes, but by the time the ski patrol got there I "felt" much better. I took the trip down in the boat and was checked out at the first aid office. At this point I had yet to place any weight on my knee and my knee felt a little pain but not much. However, when I got up my knee gave out, but instead of going forward as a knee should it gave out going toward my other knee. My knee continues to feel okay expect when I place weight on it, every time it gives out in this way and that is very painful. I am wearing my roommates hinged knee brace now and it still has ways of maneuvering to give out. Does this sound like any thing more than a muscle strain that should feel better tomorrow?