Brief Answer:
Severe muscle spasm may be the cause

Detailed Answer:
Hello
Thanks for posting
Your symptoms are suggestive of severe muscle spasm (Trapezius muscle) leading to restriction of neck movement. Do you have any pain in upper limb with numbness and tingling sensation? Please share in your reply.
Meanwhile hot water fomentation, Ibuprofen along with muscle relaxant like thiocolchicoside helps under medical guidance.
Hope this helps and I shall be glad to answer any further query.
Take care

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Brief Answer:
Pain of cardiac origin has following symptoms

Detailed Answer:
Hello
It’s good to see you
After going through the whole discussion, it seems your main worry, is to know whether this pain is of cardiac origin?
The cardiac pain is present in centre of chest with radiation of pain in left upper limb to neck and jaw region. It comes on with mental stress/physical work, very severe and may be associated with sweating. Do you have that? Any family history of cardiac disease and hypertension? To allay all your worries you need physical examination, ECG and TMT and if possible supplemented by lipid profile.
In comparison if you have muscle spasm, there is pain with restriction of neck movement.
I hope this helps to reach some conclusion. If you still have doubt you may send your query I shall be glad to answer them or you may please close the present discussion.
Wishing you good health.

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