My first question is: What are your current levels of B12 and D? In order to know what you should be taking, you need have a baseline. Hopefully you've already had these tested. If not, please get them tested before you begin supplementing, so you know where you are.
Please don't rely on your doctors to look at your labs and just tell you your levels are "normal" - because common medical standards for "normal" both of these vitamins often are way below the neurological protective level for things like MS. Ask for copies of your test results. Look at them yourself.
In general, your serum levels of vitamin D should be around 80-90 ng/ml. And your serum levels for B12 should be around 1000 (forgive me, can't remember the unit of measurement).
I make sure I get about 30mls of flax oil a day, along with 3 servings of oily fish a week - following the diet and supplementation protocol implemented by Dr. George Jelinek (
https://overcomingms.org/recovery-program/). He has a book called "Overcoming MS" that details his protocol and his research. There are also other MS diets you should research. Almost all of them require some fairly major dietary changes. There are differences around the edges, but many of them recommend a diet very low in saturated fat, and the one thing that's common to all of them is NO DAIRY.
Fish oil is excellent. But according to the HOLISM study (
https://overcomingms.org/holism-study/), daily flax oil + 3 servings/week of fresh oily fish reduced relapse rates more than flax oil alone, or fish oil alone.
Jelinek's plan is essentially plant-based whole food, non-dairy pescaterian, with little to no heated oil, very low saturated fat, plus high levels of vitamin D, and omega-3 supplementation. I was already eating basically vegetarian when I got my diagnosis, so it was less of a major change for me, but I do miss cheese.....
Obviously I'm biased because I choose his program over the others, but I encourage you to take a look at it and make your own decision. Other common diets are Best Bet, Swank, Wahl's. Like most things with MS, the choice is a personal one, with no definitive right or wrong answer.
As other people noted, other than that, what supplements you take is up to you. Read a lot. Decide what's best for you.
I personally take:
10,000 IU D3 (this is an experimental daily dose - I may well be adjusting after my next blood test next month)
2000 IU B12 (same as above)
600mg magnesium (because I am taking so much D)
100mcg K2 (again, because I am taking so much D)
A good multivitamin
Probiotic
acetyl-l-carnitine 1000mg + r-lipoic acid 300mg (to help regenerate nerve damage)
and a cocktail of antioxidants, including:
coq10 100mg
n-acetyl cysteine 1200mg
curcumin
...I think that's it.