Musculoskeletal Strain or Sprain: Given the patient's description of muscle tightness, sharp shooting pain, and the chronic nature of the pain, a musculoskeletal strain or sprain is the most likely diagnosis. This condition is common, especially in individuals who may have poor posture, engage in heavy lifting, or have experienced trauma, which could be exacerbated by the physical demands or environmental factors associated with being in prison.

Herniated Cervical Disc: The patient's complaint of nerve pain and sharp shooting pain up to the back of the neck could indicate a herniated cervical disc, which puts pressure on the nerves and causes pain.
Cervical Spondylosis: This condition, involving wear and tear on the discs in the neck, could also explain the chronic pain and stiffness, especially if the patient has a history of heavy lifting or repetitive strain.
Fibromyalgia: Although less specific, the widespread muscle pain and chronic nature of the symptoms could suggest fibromyalgia, especially if other criteria such as sleep disturbances, fatigue, and tender points are present.

Spinal Cord Compression: This is a medical emergency that requires immediate attention. Symptoms can include severe pain, numbness, tingling, and weakness in the arms or legs. Given the patient's description of severe pain and the fear that their neck might "break," it's crucial to rule out spinal cord compression.
Meningitis or Encephalitis: Infections like meningitis or encephalitis can cause severe neck pain and stiffness, along with other symptoms such as fever, headache, and confusion. These conditions are emergencies and must be promptly diagnosed and treated.
Cancer with Metastasis to the Spine: Although less common, cancer that has spread to the spine can cause severe back and neck pain. Given the patient's age and the chronic nature of the pain, it's essential to consider this possibility, especially if there are other systemic symptoms.

Multiple Myeloma: A type of blood cancer that can cause bone pain, including in the spine, due to bone destruction.
Osteoporosis: Although more common in older individuals, osteoporosis can lead to vertebral fractures, causing severe back pain. This might be considered in the differential if the patient has risk factors such as steroid use, smoking, or a family history.
Spinal Epidural Abscess: A rare but serious condition involving an infection in the spinal canal, which can cause severe back pain, fever, and neurological deficits. It requires immediate medical attention.