What could be the cause of sudden back pain? At it's worst it radiated across the mid section of back and brought on severe shakes, vomiting, muscle aches, and burning with urination. Was seen by ER doctor who did blood work, urine test and abdominal x-rays. They thought there was a blockage in small intestine but CT scan did not show this or anything else. Was given pain med, zantac and antibiotics via IV bag but discharged with diagnosis of viral infection because they weren't able to make another diagnosis. Back pain is localized now on left side, have dizziness and weak. Could there be other reasons for these symptoms? Need to start feeling better. Thank you.