Back pain. Posterior view of a seated naked woman holding her back whilst suffering pain. Lower back pain (lumbago) is a common disorder which affects most people at some stage in their lives. Muscle spasm is a common cause. In severe cases, it may be due to intervertebral disc prolapse (slipped disc) of the spine. Lumbago is often caused by sudden turning or bending movements, but may have a gradual onset. Normal movement exaggerates the condition once it is present. Treatment is with painkilling drugs, and bed rest on a firm surface.