Believe it or not – severe golf injury

I was playing golf and seemed to temporarily dislocate my knee cap on my backswing and collapsed. In my backswing, when bending my knee slightly inward and twisting, I believe that my left knee cap came off track and slid to the right, shortly popping back into place. I now have much tenderness on the inside of my left knee, stiffness, and continued weakness (repeating the same motion, my knee again gave way, once again as if my knee cap slipped out of its track). There is no inflamation, and the pain is lateral motion dependent, it is not consistent or throbbing. I can also walk up and down stairs without much pain, but if I twist the wrong way the pain is severe. Any thoughts would be helpful. I’m planning to see a doctor tomorrow. Sorry about the length of the message.

THANKS in advance for any advice!
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Christopher B