What could be the cause of a pain w/numbness in the left pelvic (back to front pubic) area w/ stabbing pain where torso meets thigh?

Back lesion as cause: With a pinched nerve supplying that area of the body, due to arthritis, slip disk, injury or space occupying lesions in the spine. Another common problem is meralgia paraesthetica, where a nerve to the front & side of the thigh gets trapped under a tight ligament against the iliac bone(pelvis). The symptoms you mentioned are most likely due to it. See your orthopod for proper DX and treatment.