Progesterone

So after a couple Mcs back to back, my OB suggested progesterone, 400mcg a day. Does that sound like a lot? It says on the label it can cause headaches, drowsiness, and nausea. I started it on Tue and was fine until today. Ugh I feel yucky all over. Kinda like I did before I miscarried - only there is no blood so I'm not hitting the panic button.. any one else want to chime in with their experience on progesterone?