3 years ago (pre-MS) I stopped drinking diet drinks (except the occasional Tab which has saccharine not NutraSweet) because the NutraSweet was giving me daily headaches. I don’t know if it affects MS but I think it is bad stuff, I only use sugar or sweet and low now.
Of course, when I got MS (just this spring) I also got migraines at the same time, oh well! (At least it’s not every day!) 🙂