On one hand, Iodine will give the body more endurance. On the other hand, Iodine can relax you as the body temperature stabilizes.
If that's what Iodine will do, then maybe you're seeing what the detox is causing, not the iodine. Fatigue. It has happened to me in the beginning of my journey. It still happens once in a while.
I'm not familiar with the form of iodine you are taking. I assume it is iodine without iodide. Not that it makes a difference with this symptom.