The causes of neck and shoulders pain 

• Poor posture which leads to pain 
• Shoulder-blade movement  disorders : This occurs when you work too long time in one position or continuous hand movement.
•  Rotator cuff tendinitis in the shoulder joint: Occurs when you play sports, hand over a strong lead to tendon in the shoulder joint injury.

• Tuberculosis: Tuberculous bacteria attack the joints causing inflammation of the spine leading to dull shoulder pain.

• Neurological disorders: Fatigue of neck and shoulder fatigue can occur due to nerves running through the shoulder area is over-stretched or injured.
• Injury: Shoulders and neck injuries such as heavy knocks or poor exercise can cause neck and shoulder pain

Another: 

• Sitting air-conditioner too cold, wind blowing on the nape
• Napping on desk
• Using computer in along time 
• Driving with poor posture
• Sleep with high pillow