menses early and terrible cramps

i took Iodine for 3 days and had various yuck effects i've written elsewhere, but my period also came 4 days early, (after 2 days of iodine), and around day 5 i had the worst cramps i ever felt - similar to when i miscarried. the sort that make you wonder do-i-need-urgent-surgery, twisting pains for around 50 minutes, then eased off to whole body aching for a day or so. i never have cramps usually (in over 20 years). period is also heavier and longer.

i've searched the forum and found other women have indeed had this type of reaction, but nothing about how long it could last, or WHY???? Tweet