Your mother appears to be suffering from arthritis for a long time. The pain in her arm may be caused by joint inflammation which indicates that it’s a nerve problem if she experiences discomfort in the stomach too. When people have arthritis, sometimes they undergo a situation where nerves get affected hence feeling pain in different body parts apart from those with affected joints. To minimize the pain she is going through she should do gentle exercises, use warm towels if possible, and get drugs prescribed by a physician. 

you should get medical help immediately. Contact your orthopedic surgeon and follow medical advice given. Indeed, delaying treatment causes only more problems.
 

A bulging disc pressing against nerves can cause pain and affect your balance. Falling is dangerous. You better go back to the hospital. They might have to change your medicine or try something else.