Upper Left Hand Arm Pain. Medication!

My mother has a constant complain of pain in her upper left arm (above elbow and below left shoulder). Pain is tolerable and not severe but it disturbs her whenever she is falling sleep. Earlier for a few months, she had pain in her elbow joint which she now says has been cured. She has a suspicion that because she is not a stomach side sleeper but sleeps with her arms beneath her body, this pain happens. Unfortunately she is unable to change her sleeping position. She does not suffer from any disease or condition, her BP is normal, diagnostic tests for sugar and other parameters were done last Oct 2015. Her Vitamin B12 an Vitamin D3 levels were low and after doctor's consultation, tablets were prescribed at that time. She completed her dosage and is now not taking any medication