Originally Posted by madmike23

I'm in X-ray, work with orthopedic doctors and I've seen many people with hip or lower back problems. I'd say go see a doctor. If you feel a sudden pain through your back and/or legs, it could be your SI Joint. Riding with your knees high can cause more bending of your lower back/pelvis. Being a big guy and cramming yourself in such a tiny space can hurt in the long run.