Hi welcome to Health care magic forum. The pain could be either arthritis
of the shoulder or spondylosis
of the cervical spine
,or prodromal symptom of herpes simplex
I advise you to consullt an orthropedic surgeon, to exclude or diagnise arthritis, or spondylosis. If these 2 are not present, then it will be herpes infection and pain relieved in few days. disease may take some time for complete cure.
Besides i advise you some diet recommendations as avoid taking potato, other tubers,tomato, egg , chicken, fish, and sea foods till you get complete relief of the pain as these tend to increase the existing pain.
Wishing for a quick recovery of pain and the causeof the pain, and thanks for calling.