Sudden pain in the neck that prevents movement may be due to the following two reasons: 1. It may be caused by a sudden backward protrusion of the cervical disc that compresses the dural sac. Usually the compression of the dural sac leads to inflammation and edema of the dural sac, which stimulates the muscles of the neck, resulting in pain and stiffness of the neck muscles with limited movement. 2. It may be a misalignment of the small joints of the cervical spine, which is usually accompanied by long-term strain on the neck muscles, resulting in an imbalance of the neck muscles, which can easily lead to misalignment of the small joints, which usually occurs with a little inappropriate force. If you want to confirm the diagnosis, you can usually go to the hospital to check the local X-ray or CT of the cervical spine, which can basically confirm the diagnosis.