i think you are down into the "everyone is a little different" category.
i think you are simply waking up some dead olfactory cells. Iodine is necessary for sweating and it does come out in sweat. i find that i must adjust dose for changes in the environment. keep paying attention and trust yourself.
if you want to clean up the sinuses even more, try oil pulling. what a great thing to do while driving.
as for the stimulant part, Iodine makes everything work better. will you get used to it and miss it if its gone? yes. is this addiction? well, it is for me. im addicted to good health and a sound mind.