you might be interested in investigating your magnesium status. ms patients tend to have lower magnesium levels with links to spasticity, fatigue, and about 300 other things going on in your body!
normal range is 0.70-1.10 mmol/L. levels should actually be at least 0.90 mmol/L.
you can boost dietary magnesium, and take an absorbable supplementary form such as magnesium glycinate.
magnesium oxide has the highest percentage of elemental magnesium, but it's not very soluble so it just goes right through you. beware!
magnesium citrate is one step better than magnesium oxide. it's a good one for taking at bedtime. 'natural calm' makes a nice product, just powder you mix into hot water, available in a wide variety of flavours.
i don't recommend magnesium glycinate for bedtime. i take that form before a large meal instead. yes it's the most effective, but if i let it linger in my stomach, it relaxes my LES, and i end up with acid reflux and a related nasty cough.
if you high-dose vitamin d3, you need to be careful with magnesium. take some of your daily magnesium with the d3, but ensure you take in some magnesium separate from d3.
magnesium has a lot of things to do in the body, but when taken with d3 it tends to only do its d3-related jobs and skips the rest.