This treatment is being suggested on bases of the information provided. However I would like to examine & investigate you  in detail. -Control  Hypertension, Diabetes or  metabolic disorder, if there is any. -Any way it may be tried, --. Dolokind Plus (Mankind) [Aceclofenac100 mg +Paracetamol 350 mg] 1 tab. OD & SOS. X 5 days. --. Caldikind plgus  (Mankind) 1 tab OD x 10 days. -(You may need help of your local doctor to get these medicines.) --. Fomentation with warm water. Let the part not be exposed to cold. --. Sleep on a hard bed with soft bedding. --. Use no pillow under the head. --. Avoid painful acts & activities. -- .Do mild exercises for the affected part-ie. back And shoulders --.(Take help of physiotherapist or you can visit my you tube channel drncgupta.  Yoga Simplified  and me and my yoga --Do not ignore, let it not become beginning of a major problem. --Do ask for a detailed treatment plan. Kindly make sure, there is no allergy to any of these medicines. --For emergency treatment visit nearest hospital. --Wish you a quick recovery & good health. --I hope, I have solved your problem to your satisfaction.  Dr N C Gupta MS (ortho)

If this is recent then will subside with painkillers. If not and a routine feature then may require further tests. Consult if needed.

This might have happened due to acute spasm in lower neck and upper back muscles causing stretching of the nerves supplying the shoulder and upper limb.. Has this happened for the first time or it has occurred previously also..