Brief Answer:
Spinal surgeon's advise & self care would help.

Detailed Answer:
Hi XXXXX,
Thanks for the query. I have read your query carefully & understand your concern.
It's good that you have provided your X ray & EKG reports that short lists your basic problem.
* In my view your symptoms are due to pressure/ irritation of nerve supplying the part ... causing the tooth ache like dull pain & heaviness in arm & shoulder& also the pain in back.The pressure can be
- At neck level ( cervical rib ) or
-Cervical spine problem - May be degenerative due to age causing disc prolapse ( on left side )
- Or inflammation & infection of the rib itself ( pot's spine ) which seems to be a rare possibility in your case....causing damage of the spine & disc .. such a condition is associated with low grade fever/ loss of weight / low appetite over a long period .. as you do not complain of such symptom.. still it's considered due to the pain you have after pressing a specific point & should be excluded.
* In this context I would suggest consultation of a spinal surgeon. after detailed physical examination,he would advise your blood counts/ X ray , MRI or CT scan of cervical spine to locate exact site, nature & severity of problem.Even the pot's spine can be excluded by these investigations.
* The treatment would be according to the cause. It would be -
- Medicines anti inflammatory medicines NSAIDs.. like Ibuprofen/ vitamin B12/ Vitamin D & calcium supplement.& specific drug regime for spinal infection if any.
- Physiotherapy ,
- Surgery as per indication & gravity of the cause.
Self care-
- Do not bend your neck down, keep it erect.
- avoid lifting weight,
- avoid physical or psychological stress,
- Strictly follow the medicines & physiotherapy as per expert advise.
Please don't worry.A methodical assessment & expert advise with self care would help you to manage your problem.
I hope, you find the answer both informative & useful. Any follow up query is welcome.
Please close the answer & grade it when you are satisfied.
Thanks.

---

Brief Answer:
Flexeril symptomatically treats the muscle spams.

Detailed Answer:
Hi XXXX,
Thanks for the follow up query.
Flexeril is a muscle relaxant which relieves muscle spam, ( caused by nerve irritation or compression as described before/ excessive muscle strain/ trauma to the part). Ideally it is accompanied by physiotherapy.
I feel you should continue with the treatment offered by your doctor. & weather you are relieved or not.. should get investigated by at least X ray to exclude cervical spinal problem( which is more likely at the age.),in order to prevent repeat events in future.
I hope you got my point.Any more information you want I would be happy to help.
Thanks.

---