Hi Noah, and welcome to the community!

Perhaps I missed it in your post, but was the doctor you saw a specialist? A neurologist? If at all possible, I would get a second opinion from an MS neurologist. There might STILL not be enough "evidence" for a definite diagnosis, but I'd want a specialist to say that.

There's something new coming out for information all the time, but I never heard of meds potentially neutralizing future meds. I'll have to do a little research on that, for my own satisfaction.

It IS quite common for an MS diagnosis to take a while since certain criteria have to be met for an official diagnosis. It took me a year and a half, and others have waited much longer. It's frustrating, but not unusual.

Vitamin D is recommended for those who do have MS from the literature I've seen, and I think there have been studies suggesting (I repeat, suggesting) that people low in Vitamin D might be more susceptible to MS. But I'm not up on the latest about that.