This could be due to any of the following:

1. Loss of bladder or bowel control — could suggest cauda equina syndrome, a medical emergency.
2. Severe back pain radiating down the legs — may indicate nerve compression or herniated disc.
3. Numbness or weakness in limbs — sign of spinal cord or nerve root involvement.
4. Sudden paralysis or inability to walk — could point to acute spinal cord injury or stroke.