My dizziness is always worse during my period, and I'm almost 3 years post. I don't know why either, but it's pretty predictable. In fact, it starts about a day before the period actually starts. While I had the IUD in, and for about a year after removal dizziness and vertigo happened all throughout the month. The vertigo is gone now, but the dizziness creeps back during my period. It comes with a tingling/buzzing feeling in my head often as well. It's quite lovely.