The reasons why you can’t tilt your neck back especially hurt like a pillow fall include cold, strain, trauma, cervical spondylosis and herniated disc. 1. Cold: prolonged exposure to low temperature or humid environment will hinder the blood flow in the neck, resulting in stiffness, pain, and restricted movement of the neck. 2. Strain injury: Shoulder and neck muscles, ligaments and other soft tissues are damaged due to long-term low head work and carrying heavy loads on the shoulder, and the damaged soft tissues are pulled when leaning back, which will cause obvious pain. 3. Trauma: Including sprains, pressure injuries or collisions, etc., the soft tissues or bones are damaged, resulting in pain when tilting the neck back, swelling and redness of the shoulders and neck. 4. Cervical spondylosis: caused by degeneration of joints, long-term strain or maldevelopment, etc., manifesting as pain and stiffness in the back of the neck, accompanied by weakness of the upper limbs, dizziness, nausea and so on. 5. Herniated discs: occurring in pregnancy, disc degeneration or acute trauma, etc., the protruding discs compress the spinal cord nerves, appearing neck pain, numbness in the hands and feet, walking instability and so on. If the neck can not be tilted back especially painful after resting this symptom can not be relieved or even continue to worsen, you should go to the hospital as soon as possible to see a doctor.