I'm brand new to the forum and Iodine in general however I've read almost every resource so maybe I can contribute?
First: take the Iodine in the morning especially when starting out... it will cause insomnia if you don't. I took KELP a week ago just to start and I stayed up till 5am.
The stimulated feeling is probably the jittery feeling, but you feel it in a calmer sort of way.
2,000 mgs Vitamin C
200 Ė 400 mgs Magnesium
1/2 tsp Celtic Salt
The above should help, but you need to make sure you are taking the proper forms. For instance, unrefined Sea Salt (that is white) doesn't count. Magnesium oxide doesn't count... you ideally want a glycinate / bisglycinate form of magnesium (or magnesium chloride). Vitamin C needs to be ascorbate / ester c / liposomal.
How much water exactly are you taking? I would also read up on the 100mg Iodine theory... it could be that too much bromide / fluoride is getting into your bloodstream.