So it appears that the headaches start when the estrogen is at its lowest and continue until the estrogen levels start rising before ovulation.
It sounds like your estrogen levels are unusually low, which can cause debilitating headaches. Some women have found relief from these cyclical “low estrogen headaches” from taking magnesium supplements. Ask your doctor about it. Taking a magnesium supplement sounds safer than adding synthetic hormones to the mix plus all of the other risks that come with the Mirena.