I've always gotten cystys behind my ears when my estrogen levels are too high. I know this because they almost always show up around my period. And when I was taking an estrogen clearing tincture (coptis), about 5 broke out and stayed for well over a month until my body was able to clear things up.
As we all know, Iodine and hormones are connected. And then there's your pregnancy....
The liver clears excess hormones. I'd recommend taking some bitters and doing a liver flush.