For years I had muscle spasms in my lower back and tried Lugol's Solution, but it made me very nauseous so instead I switched to Potassium Iodate by Vitamin Research (you can find it on Amazon). It comes in capsules of 50mg, but since it's in a Potassium Iodate solution, only about 24mg of the iodine is available for absorption. Best of all, it acts like a buffer slowly absorbing into your system. At first I took it at night, but after a week or so it started keeping me up at night, so I switched to taking it in the morning with my Breakfast.
I don't even need coffee anymore and the pain and spasms in my back are completely gone!