@jord. You are a great friend to your friend! Right now, you can just be there for her. Listen to her, let her cry, whatever she needs. Do you live near her? Giving rides would be very important. As for medications, let her doctor make those decisions with her input. Read all the rest of this discussion (and others that you will find here) and you will learn how others cope. You can even suggest that she join group and see that she is not alone.
I, too, was diagnosed with an autoimmune disease that, at first, looked like MS. A brain biopsy showed that it was another disease not MS. The one thing I really wish is that I had a friend whom I could talk to. Most people don’t want to talk about my disease because it makes them uncomfortable. But, you could be that confidant for your friend! Give her as much support as she will allow.
Think you could do that?