Sorry, I've got no info for you about iodine, but...
Have you tried mucuna bean powder for the muscle spasms? It is what helped my muscle spasms. It is a natural source of L Dopa. Don't know if it would be appropriate for your case, but perhaps it is worth researching. One must be careful of dose, as too much can cause panic attacks--even if not immediately, then maybe over a while of dosing.
My muscles spasms were either from Lyme, or endocrine problems, or pharma side effects... probably some combination of all of em. Face, arms, legs. Used to keep me up at night.