Ah yes, the MS Itch....sounds like a dance..
I have exema on the palms of my hands and that itches like crazy. But I also have, what I call Nerve Itches, that are under the skin and you just can't reach them.

I use Calydryl Clear (calamine lotion), and it almost immediately stops the itch......for awhile.
Good luck in finding a good remedy and when you do, post it here.