Hello,
Sharp, 
stabbing pain in neck, shoulder and upper arm is commonly due to overuse injury of the shoulder, 
shoulder tendinitis, bursitis, impingement, etc. 
Cervical radiculopathy or 'pinched nerve' may cause similar symptoms. This causes 
radiating pain into the shoulder and numbness down the arm and into the hand. Your symptoms may be indicative of  
brachial neuritis that causes severe pain in the shoulder, arm, hand and neck as the nerves run from the spinal cord along the neck.
You are suggested to get clinically examined by a GP, an EMG can help detailed study. To make sure that no other injury, such as a cervical 
herniated disc, is behind the pain, an MRI scan is done to rule out compressive lesions. Treatment for Brachial neuritis includes methods for controlling the pain, healing the nerves and 
rehabilitation. The treating doctor may give pain reducing medications  like oral steroids, narcotic medications and neurotropic medications such as Lyrica or Neurontin to stabilize nerve membranes and control pain. Proper rest and reduced physical activity is also recommended to ease the inflammation and pain.
Take care. Hope I have answered your question. Let me know if I can assist you further.
Regards,
Dr. Nupur K., General & Family Physician