This is a bit of a guess, but when my migraines first started (30 years ago), they would start a day or 2 after my period started and would continue until ovulation. The next year, i had a bone marrow biopsy and the only issue found was that my iron in my bone marrow was non-existent (no iron staining at all in that test). So again, guessing, you might want to try to boost your iron during the peak 3 days. If it works well, then the next month, try it for the peak 3 + 2 more days. Trying most things slowly should allow you to see if it works and what the negative effects are. Also eating things rich in iron is more safe than taking supplements.

I use body armor. Nothing really takes it away but try that.

Along that line, i started using "liquid iv" hydration mix each morning. 20% sodium and 8% potassium. It too is not a miracle cure, but it is definitely helping. I can even see it in my skin. Since my POTS, my skin can go from normal to creepy skin to staying indented to looking like fine waves on a lake, etc within hours. This seems to have stopped that. So, i assume, it means that the water I'm drinking is finally getting out to the skin.