What Causes Shooting Pain In Back With Muscle Spasms?

I broke my coccyx twice during childbirth. Since then I have had so much back pain. I cannot sit in a folding chair because the bar across the back sends shooting pains up my back. My Pcp told me I am having muscle spasms. I tried Physical therapy, Motrin 800, Mucsle relaxers which I still take because I have very bad TMJ. Could the break be causing all this pain? I am 31 years old and everytime I try to Play with my children I feel out of commission for a few days after let alone the normal struggle I have throughout the day. I feel as though my pretending I'm fine is getting harder and harder. I need help.