I'm also experimenting with high doses of vitamin D (10.000 iu/day, maximum safe dose for an adult). Vitamin K2 also added as a precaution against calcium metabolic disorders. Some papers suggested that it could repair nerve damage to some extent, plus make MS milder in general. Doing this for 3 months already, so far so good, I can feel some improvement of symptoms that I have as a result of nerve damage originating before start of DMF treatment. Of course, can't tell for sure it this is related to vitamin D or not.
Will publish updates on this. So far, I'm using myself as a lab rat and I discourage people from doing the same unless they are very sure what they're doing.