Does anyone know of either, or both, of these medications will cause your period to be late? I had mild cramping and MAJOR back pain on CD 27 & 28 so I thought my period was coming. I've always been a 27-28 day cycle kinda girl. Since the cramps and back pain I've had zero pms symptoms. I've been doing a test every morning and they've all been negative. I just need to know if I need to call my fertility dr on Monday morning if no AF, or if this is normal. I'm on cd 32.