Sir, apologies for the delayed response, the problem you have described is very little information to exactly jump on to conclusion of what to suggest you or what not.
certain things that are relevant would be (are you still employed or not ) what are the tasks that you do , and since how long the pain has been , how is your posture, and also what relieves the pain. a thorough assessment is required.
if i assume all the commonest causes and most common scenario for this debilitating condition, it might be frozen shoulder which has progressed and now stiffness in trapezius muscle.
for it manual exercises are to be done by an expert therapist otherwise you may end up injuring your rotator cuff muscles and end up in pain and distress.
Next Steps
seek online consultation else visit the nearest good clinic. for a better understanding of your condition.
Health Tips
DO NOT IGNORE THE PROBLEM > SEEK IMMEDIATE CONSULTATION. from someone specialising . (he / she will not only put you on machines.). Stay healthy