Hello,
This usually happens when a nerve gets compressed between your spinal bones.
Once the pressure on the nerve is released your pain will slowly go down and get relieved.
Next Steps
I would suggest you to take Physiotherapy treatment for 8-10 days.
There is cervical traction machine treatmet for your neck, this will help relieve the pressure from that nerve. this machine treatment combined with some simple streching exercises should be helpfull.
Health Tips
do not jerk your neck or shoulder or hand when the pain going down ur hand feels irritating as it might increase the pressure on the nerve.