I have studied your case
As per your history there is possibility of shoulder arthritis
Since ESR is raised suggest long term ongoing disease process.
Another possibility of early shoulder pericapsulitis can be considered.
You need clinical examination from orthopaedic surgeon
to know the origin of pain and investigation accordingly.
Investigation like MRI cervical spine/shoulder, EMG-NCV [Nerve conduction study], CPK and x ray shoulder with humerus
I will advise to check your vit B12 and vit D3 level.
You can consult physiotherapist for help.Physiotherapy
and interferential therapy will give quick relief
Strengthening gradual exercises will help in reducing pain.
Hope this answers your query. If you have additional questions or follow up queries then please do not hesitate in writing to us. I will be happy to answer your queries.
Wishing you good health.