18 wks pregnant with constant left lower back pain. goes away while sleeping but reoccurs during the day. no pain pills,don't want to become dependent?

Tylenol if safe.: You won't become dependent on it, but you should visit your doctor to determine the cause of your pain. That it's worse when you're active during the day hints at a musculoskeletal cause; once any other possibilities like infection or pregnancy issues are ruled out, you could also try massage, acupuncture/acupressure, ice, heat, or specific stretching exercises. Good luck!