What causes backache?
Backache is usually caused by minor strains in the muscles, ligaments or joints. More serious lower back pain may be the result of an injury to one of the many joints along your spine. The joints include the facet joints and discs, which when disturbed can push against painful tissue or nerve roots just behind them and may cause neuralgia (nerve pain) that can radiate down limbs. The injury usually happens while bending your spine forwards (flexing it), especially while lifting something heavy.
Other causes of back pain are arthritis, osteoporosis, cancer and structural problems.