Being that its not a back injury, I have a friend who is a male, and he had a vasectomy, and right after the procedure, give a few days, he started experiencing the same thing as you, and the doctor told him its prostatitis excuse the spelling, any way its something that wont go away, the only thing the doctor told him was to avoid caffeine, and alcohol, hes gone for different testing, different doctors and all said the same thing, im not sure if you have done any research on this, but evidently thats one of the symptoms, hope this helps, good luck, hope you find the answer your looking for, I unfortunately seem like im the only one that has this problem because of my back injury, trust me I know exactly what your going through, I know it sucks, its depressing, but I wont give up until I get my self back to 100%,