It never ceases to amaze me how little people know about the herxheimer reaction. I need to get more involved here to teach. It isn't rocket Science people.
Herxheimer reaction is caused by one thing; endotoxins. Gram negative bacteria death remnants. Not bromide poisoning or any such crazy tales. Detoxing (killing gram negative bacteria) is great but be careful because it can kill you if you get too many endotoxins in your blood. Take it slow. At the first sign of herx take 1 tbsp Activated charcoal mixed in water. It will stop the herx in its tracks by adsorbing the endotoxins.
The reason why the iodide/elemental Iodine worked to give you a herx is simple; it is killing your intestinal bacteria. This is a good thing. The dermal application didn't because it didn't get inside your intestines to kill bacteria. The reason why nascent didn't work was it is a different form that doesn't kill bacteria. Once you understand the basics, everything makes sense.