Neck and shoulder pain. Posterior view of the head and upper back of an Afro-Caribbean man, his hand held to his aching neck and shoulders. Neck and shoulder pain and stiffness may be caused by spasm of muscles in the neck and back. More serious is a whiplash injury of the neck in which soft tissues, ligaments and spinal joints, are injured due to the neck being suddenly and forcibly bent. Neck fractures and slipped disc may also cause considerable neck pain. Treatments of milder forms of neck and shoulder pain include use of painkilling drugs and massage.