Ive just done a quick bit of research, and while it it is used to control irregular periods, it is also used to POSTPHONE a period. Not sure of the logistics of it, but it is actually a contraceptive. Also goes by the trade name Primolut N. Its a progestogen.
Hope that helps? Sorry I cant be of more help with the side effects, have you tried water crackers and ginger products? Im on pain meds that often cause nausea and I find these to really help.
Best of luck!