Vomiting every menstral cycle, what's wrong?

Menstrual vomiting. Nausea and vomiting during menses are not uncommon. However, the intensity you describe deserves proper evaluation. Examining your dietary patterns and taking nsaids (ibuprofen, naproxen) a day or two before menses may help. See your doctor.
CVS. It may be due to cyclic vomiting syndrome (cvs), which is characterized by episodes or cycles of severe nausea and vomiting that last for hours, or even days, that alternate with intervals with no symptoms. Episodes of vomting could be triggered by anything stressful like menstruation. It often coexists with migraine headaches, and can be controlled by medications to control vomiting +/-migraine.