I dont know, as it is a mix of several homeopathics and 150 mcg in colloidal form, which is what we (should) get from food daily.
Could just as well (probably) be one of the homeopathics that kicked in. I never liked the mixed kind like this, even long before iodine; as we never know which of them that actually did the work.
"Thyadine delivers 150 micrograms of colloidal Iodine in each drop. It also combines homeopathic elements such as Fucus Vesiculosus 3x, Thyroid 3x, Spongia Tosta 12x and Thyroid 30c to deliver a synergistic thyroid-supporting formula based both on nutrition and energetics."
From your symptoms; I would definitely prefer no PMS / bloating before being on the exact date. And I would give the remedy some time to work, like 2-3 periods before I concluded much.