When I began with the Iodine protocol I went through a similar phase with my skin all over my body. I didn't get a rash per se but I was itchy like crazy everywhere and what really helped me was to make a solution of Lugol's and water (10 or so drops--didn't really measure-- to about 3/4 cup of water) shaken in a jar. I used this solution like a skin lotion and put it all over my body and the itching would miraculously stop for a while. At first I had to do this many times during the day for a few weeks. When I didn't have Lugols I used the drug store brand and that worked also.
Hope this helps. I just kept pushing through all the detox and persistence has paid off for me. I was scared but determined to gain some control over my health and I trusted the people here on this forum as I read everything (200 plus pages here) I could and knew that I was led here for a reason.