I have had it happen many times and it seems that every few years I am nausea a little before and during my period for about 6 months, then it goes away for a year or more but comes back. It has to do something with the hormone levels, being on birth control sort of helped me but then I felt crazy on the pill so stopped. Now when it happens I treat it like morning sickness, when I wake up and feel nauseous I eat a few crackers and slowly get up, I also have those preggo pops (suckers and hard candy) which has herbs that help ease the nausea feeling (sometimes it works sometimes not). I have found the preggo pops at various baby places like USA Baby & Babies R Us.
I have had this off and on since high school (now 28, so roughly 12 years), and I have an odd period which we tried to stabilize with birth control but that made me feel like I was crazy and mean to everyone around me. My hormone levels also jump around more then they should which is why the OB/GYN thinks I feel nauseous sometimes during/around my period (just like morning sickness when someone is pregnant).