I am so sorry to hear about your mother and all she's going through, she is close to my age, and I can tell you that is too young to be going through all that!
Having my own mother suffer with MS my whole life I know the feeling that you have of helplessness...
It sounds like she may be having some anxiety and there might be something she could take for that?
It's hard to know what causes what and sometimes doctors seem even clueless. I'm sorry I can't offer any advise to you only prayers and sympathy and hoping that there is some resolution to her latest challenge.