Hi. With the symptoms you have noted , it looks to be spasm of neck muscles causing entrapment of nerves causing the problems you are suffering from. another likely problem can be spondilitis of cervical ( neck) vertebrae. Ir needs minimum an X-ray, and preferably MRI
of neck spine. In the mean time you can try to lift, support and hang the left elbow in a sling to be attached to the right side of the neck. This will transfer all the weight to the other part of body thereby giving you relaxation of the affected muscles. Carry this on for as much time as possible in a routine day. This helps all my patients. Continue the medicines as per you Doctor's advise.