In all types of MS, fatigue is one of the commonest symptoms, but unfortunately also one of the least understood and hardest to treat.
I'm not optimistic that vitamin supplements will make much difference, particularly as you haven't been shown to have a deficiency in the first place.
Lots of people with MS do choose to take vitamin supplements anyway: Vitamins B12 and D3 are common choices. But I think more people take them for their presumed protective effects and/or possible role in repairing MS damage, than as a treatment for fatigue, specifically.
Personally, I take loads of vitamins (could open a shop!) but I've never felt they are lifting fatigue. In fact, I've never FELT they are doing anything, but I just have to be hopeful they're working away behind the scenes, with invisible effects, and that I'm not wasting my money completely.
There are drugs prescribed for MS fatigue, although I haven't tried them. One of them is amantadine.
The other common one used to be modafinil, but I believe there's recently been a clamp-down on the prescribing of this, because it's not licensed for MS, so it's become a lot harder to come by.