Knee Trauma

I was hit by a car as a pedestrian over 6 months ago, my knee hasn't stopped spasming since. My X-rays were clean, my MRI only showed bone bruises and a pre-existing cyst. Nothing stops the spasms - it hurts the same if I'm moving or not. My Dr. seems to be hoping it will cure itself, but I think it's getting worse. My knee pops daily and clicks when it moves. I'm feeling frustrated, and the pain keeps me up at night. Any ideas (besides get over it)?