I was going to post about the effect of magnesium on obstipation, but Missj beat me to it.
Seems Erika has it nailed! Of course it is a nerve problem, caused by your basic disease! It's common in MS. I had it very very badly during all of my young years. I did take a mild laxative and stool softeners and usually those would make me go, but occasionally I would get an absolute block, not associated with anything other than the disease. So I would have to go get manually unblocked. This happened several times.
The first time I went for a whole month without a movement. I can scarcely believe that I wrote that last sentence. Surely it must be wrong? I was only 17, and I suspect I remember this as total block when there may have been some occasional movement,
but it was So bad that I was all swollen up and very sick, exhausted, trying to go to college and hardly able to think from being semi-poisoned by this condition. Finally I took a very strong laxative, which I would not even think of doing now, when I know I should have been manually unblocked.
Whenever this has happened, the amount of residue which comes out is astonishing. Once, in Monterey, in the ER, I actually caused a toilet to come off of the wall because of the avelanche. The entire ER staff came to look at this and were howling with laughter. But it really happened!
However, since I started taking a lot of magnesium to stop spasm and jerking, I have never had a session like that again. Usually I have mild diarrhea. It's mild enough so I don't mind it, but I do eat some blackberries to counteract the diarrhea.
I'm surprised that anyone is surprised at this happening with MS. It's one of the chief
features!