I had the same symptoms and it turned out to be a torn meniscus. The little torn flap flops around and gets caught in things. I'd vote for going to the doctor sooner than possible.
Please do not start. I have already explained to someone else that my reply used medically accepted terminology. The only reason you feel my reply was out of place it that you were embarrassed or upset. It is not me, it is you that has the problem
