HI
Greetings from Dr.Divakara.P
Thanks for posting your query.
Thoracic outlet syndrome can cause these symptoms but it is a rare disease when compared to other possible causes of your problem.
Your problem seems to be due to a condition called
Cervical Radiculopathy. It is a condition in which there is compression of a nerve near the back of your neck. This nerve gives sensation to back of head, neck , arm , shoulder , hand , palm , chest and back . Due to compression of the nerve you are getting pinprick like sensation over this region.
The treatment depends on the severity of the problem . Treatment includes medicines ,
Physiotherapy,
Cervical collar applications and in serious cases Operation.
I advise you to get MRI
Cervical Spine to know the severity of your problem. Kindly revert back with the scan report.
Till then do slow rotational exercise of neck and .avoid prolonged flexion of neck .
Hope this information is useful to you.
Any clarification feel free to ask.