I've been taking Yaz birth control for a couple of years now and never ever miss a pill. I take one every night at the same time before I go to bed. Well, I'm in the middle of a pack right now and my period just started. I don't understand why. It's another 10 days or so before I take the white pills, when I'm supposed to start my period. Does anyone know why I'm off schedule? I thought that when you take the pill, you can't have a period until you take the placebo/white pills. The only thing that's different about me is that lately I've been taking prescription-strength pain killers for a migraine, but other than that, there's been no changes. I appreciate your help!