Welcome to the Health Care Magic
You have said many relevant things - nature of pain, precipitating or relieving factors, associated diseases, personal habits and so on.
It is probably from the shoulder (peri-arthritis
) / neck - cervical spondylosis
and so on.
have an ECG to exclude heart problem -especially if it brought on by effort.
Try to see a doctor. In the mean time, resting the part, warm compress and simple drugs like ibuprofen
Wishing you speedy recovery