hi matt and welcome to the forum.
you're right, many here share your frustration with the catch all dx of MS.
for example, CCSVI has been discussed as a separate condition here at TiMS for several years now. it has its own forum in which you'll be able to find lots of related discussion.
i have not personally read in detail, but member vesta has broken down MS into several categories which you can find pretty easily if you use the forum search to look for posts by author vesta.
there are lots of other ideas circulating here too, which you'll find as you browse the various topics.
over the last few decades, various people have provided nutrient intake recommendations, either in the form of short term protocols (such as klenner) or long term diets (eg swank, best bet, paleo, jelinek, and more recently wahls - you can find discussion on these in the diet forum).
as for b12, it is the best known and longest standing potential nutritional differential dx for ms, and in addition to its being a flavour of the month of sorts here at TiMS at the moment, it's a personal one for me. as a vegan, b12 deficiency was on my file when i was diagnosed in 06. a computer glitch meant the docs didnt see it even though i was telling them in person it was the case.
it turned out i had a much bigger nutritional issue than just b12, and that i shared a variety of nutrition issues that are common to ms patients, also that my levels were not a match for nutrient levels in healthy controls. optimizing nutrient levels (ie typically getting them into the high normal vs low normal range) is my own focus. proper hydration is a key part of that puzzle. once nutrition issues are removed, it seems to me that the docs would have a clearer picture what they're really dealing with and won't end up treating depletion symptoms with drugs rather than essential nutrients.