iodine cough

I started Iodine supplementation a couple of months ago and worked up to 100 mgs of iodoral with all the supplements, however I have developed a horrible dry cough. I'm guessing maybe not enough salt? dehydration? selenium seems to help it...if I take an extra 200 mcg or so.
Maybe I should drop back the dosage and try working back up again? Any suggestions guys? Thanks so much!!

Debbie