It's PMS, that's all. Any symptom you have when you're about to start your period naturally, you should also expect when stopping progesterone to start AF medically.
If you get put on progesterone during pregnancy, they generally wean you off slowly so you shouldn't have symptoms in that case. From what I understand, getting symptoms of PMS at that point is bad because it can mean your hormones are dropping too fast. Of course, a good OB would be bringing you in for progesterone draws to make sure the drop was controlled correctly.