Pain on Right Upper arm. For 10 days!

My mom worked as teacher in school for around 10yrs and she used to write on board alot with her right hand lifting it up.She stopped working around 7years back and from past 18months she is facing severe pain on her right upper arm.That pain is so furious that she is not able to lift anything or even pull the trolly luggage.She is not able to sleep on that side and touch her back with that hand.consulted many doctors and they told it's vitamin deficiency and she had tablets as suggested and thy all worked only when she was using and pain is back after she stopped them.Few doctors told that it's due to over heat.Can some one suggest me on what is the problem and which type of doctor to consult.Best doctor as well for same in Chennai. Attached is the prescription she used for 10 days