Since I was in an automobile accident 1 month ago, my knee has been hurting. My knee buckles and shoots pain up and down my leg. It bucked hard yesterday in the shower and I am in a lot of pain. It feels to be inside my knee, towards the back. Sometimes, the pain shoots down my shin. I had an xray taken earlier this month, but nothing appeared to be wrong. Something is very wrong. It hurts to walk, especially when I get up from sitting or laying down. I can t sleep very well due to the pain. Any suggestions as to what it could be?