Back pain with a feeling of the back being ?locked? can happen due to muscle strain, muscle spasm, poor posture, sudden movement, heavy lifting, or sometimes a spine-related problem. Mild cases are often treated with pain-relieving medicines, muscle relaxants, rest, and avoiding activities that worsen the pain. The exact medicine depends on your age, medical history, and severity of symptoms, so avoid taking strong painkillers repeatedly without medical advice. Apply a warm compress or heating pad for short periods, avoid heavy lifting, and try gentle movement rather than complete bed rest, as prolonged inactivity may worsen stiffness. Maintaining proper posture while sitting and sleeping may also help reduce strain on the back muscles. Please consult a doctor if the pain is severe, keeps returning, spreads to the legs, or limits walking or daily activities. Seek urgent medical care if you develop numbness, leg weakness, fever, loss of bladder or bowel control, or severe pain after an injury.