Actually, I'm not all that well versed. But, I do a great deal of research on everything I contemplate before doing it. This makes me an absolute expert on me.
I'm not qualified to comment on what to do with an iodine allergy. I would suggest a physician for a definitive answer (if you use the medical system). Other than that, I heard a (self proclaimed) expert on the subject on a talk radio show a number of years ago saying that you should take the iodine anyway if there was an actual radiation problem in the area if you could tolerate the allergic reaction. He seemed to think the long term cancer risk was greater then the short term allergic reaction (Again, I would consult a physycian before taking this advice seriously).
I have witnessed a short term allergic reaction to iodine. It was immediate anaphylaxis and death in the hospital setting. I wouldn't recommend taking iodine with a known allergy to it.