Question about my Aunt

Hi. I'm not quite sure that this is the perfect forum to ask this question but I'm very worried about my aunt. She has had MS since the early 80's (She's 54) and is very sick right now. The thing is, no one really knows what's wrong with her.
All of a sudden she developed bronchitis or something like it around a year ago (she's been a smoker for 30 years or so) She felt like she was having a heart attack or something in the grocery store and went to the doctor and was told she had a lung/breathing problem (different things by different doctors I think.) Well since then she's developed some really odd symptoms and no one seems to no what's wrong.
She has trouble talking now, forming words, she can't get out what she wants to say often and sometimes it takes her several tries to say the word that she wants her pronunciation is off too. Also, for some reason her thumbs don't "work" anymore, like she has no opposable thumbs. She has gone in for numerous tests, Cat scan, MRI's everything but no one seems to know what's wrong. They even put her on different anti-depressants because they thought it might be psychological. To me it seems obvious that it's a neurological problem (not that I'm a doctor or anything)
It just seems like her brain isn't sending the correct signals to her body or something.
She did used to drink diet coke all day long. Then in the late 90s when she first heard of the Aspartame/MS connection she stopped for a while but didn't notice any difference and started drinking it again after that. I asked her recently if she thought it might be the Aspartame and she told me that since she's gotten so sick she has barely had any diet coke at all and that she really doesn't think that's the problem.
My aunt is the sweetest kindest most generous person I know. It makes me so sad to see her so sick. She still spends her time taking care of stray cats and trying to find them homes (I even wondered if something in the kitty litter could be causing problems, any information about that?) And caring for her parents. I really wish I knew some way that I could help her. Any information would be appreciated.
Thank you so much,