Most people I've known with back pain related to weak or strained muscles were best helped with physical therapy. Often it means strengthening the abdominal muscles and loosening the chest/shoulders. Most of modern life is terrible for posture and is very sedentary, so this is not too surprising.

Pain is wildly complex though, and the causes are not always understood or easily helped. Some people require pills and other treatments. The amount of media animosity towards pain medication and related vitriol spewed at doctors is shocking and totally unwarranted in most cases.