I might try the Niacin flush test even though I haven't taken any supplement containing Niacin for a long while.
Any Iodine containing supplement scares me due to adrenal fatigue. And the fact that I believe the itch got way stronger after using high doses of Lugols about 2-3 years ago and stayed there till now. Actually around the same time I was using I don't know how many capsules of 5000 IU vit D3 daily(pretty sure it was 10,000 IU daily for about a month). So it could be either of thise that ramped up my itch.
Is it possible my adrenal fatigue could be affecting cortisol which could be affecting histamine? And by using IMAM I might eventually get rid of the itch?