Muscle Strain: The most common cause of neck stiffness and soreness, often due to overuse, poor posture, or trauma. The symptoms described are typical for a muscle strain, which can cause localized pain and stiffness.

Cervical Spondylosis: A common condition characterized by wear and tear on the discs in the neck, which can cause stiffness and pain, especially in older adults.
Tension Headache: Often presents with neck stiffness and soreness, usually due to muscle tension.
Cervical Facet Joint Pain: Inflammation or injury to the facet joints in the neck can cause pain and stiffness on one side.

Meningitis: Although less likely, meningitis is a life-threatening condition that can present with neck stiffness (nuchal rigidity) and soreness. It's crucial to consider this diagnosis, especially if accompanied by fever, headache, or altered mental status.
Subarachnoid Hemorrhage: A severe condition that can cause sudden onset of headache and neck stiffness. It's essential to rule out this diagnosis, especially if the patient reports a sudden, severe headache.
Cervical Spine Fracture: Trauma to the neck can cause a fracture, leading to stiffness and pain. This diagnosis should be considered, especially if there's a history of trauma.

Rheumatoid Arthritis: Although more commonly associated with symmetric joint involvement, rheumatoid arthritis can occasionally present with localized neck stiffness and pain.
Osteomyelitis of the Cervical Spine: A rare infection of the cervical spine that can cause pain and stiffness.
Cervical Discitis: Inflammation of the intervertebral disc, which can cause neck pain and stiffness, often accompanied by fever and other systemic symptoms.