Brief Answer:
Could be possibly due to nerve irritation.

Detailed Answer:
Hi, thanks for writing to XXXXXXX

Based on your description of symptoms, I suspect that you could be suffering with degenerative disc disease in your cervical and thoracic spine causing compression over the nerve roots.

In Smokers, these degenerative changes tend to be more proliferant than in nonsmokers.

I suggest you to undergo an MRI scan of your Cervical and Dorsal spine to know the severity of degeneration and to rule out any other pathology.

The general conservative management which may help in improving your condition is as follows -

- Soft Collar: Soft collar allow the muscles of the neck to rest and limit neck motion. This can help decrease pinching of nerve roots with movement. Soft collars should only be worn for short periods of time, because long-term wear can decrease the strength of neck muscles.

- Medicines: Analgesic are needed in the acute phase. Muscle relaxants are essential for relieving muscle spasms once the acute pain subsides. Neurotropic vitamins like METHYLCOBALAMINE (activated Vit B12) or PREGABALIN will help in alleviating the neuropathic pain.

- Cervical traction: may enlarge the disc space, permitting the prolapse to subside. Intermittent cervical traction for not more than 30 minutes at a time. Weight upto 8kg can be added.

- Physiotherapy: Once the acute phase of pain has subsided, Isometric strengthening exercises of the paravertebral muscles are started. Improving neck strength and flexibility with simple exercises may lessen discomfort and pain. Moist heat can be useful.

Lastly, you should Quit smoking in order to prevent the rapidity of degeneration.

Hope I have addressed your query. Happy to help further

Regards

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