Can a muscle become hung?

[Breemomma]

March 2015 I fell and caused a herniated disk and sacroilliac sprain in my left hip. After months of steriod shots, therapy (which the retraction table was possibly legal torture) come Dec I had a I- fusion. I was ok for about three months until I.began to loose feeling again in my left foot, it would become cold even. I returned to the dr. He ordered a nerve study done, according to the study everything was perfect. It is not it is getting harder and harder to stand straight up with out the si area feeling like something is stabbing me and a joining pain of what I can best describe as a hook from the back left hip through to my front left groin. It is getting more and more painful each time these spells happen. What could possibly be going on and is it possible to have something catching as it only hurts when.I go to straighten up?