Period Question

I was just wanting to know how common nausea is with women on their periods. I've seem to feel nauseous everyday that Ive been on it this month; tomorrow should be my last day. Just something I was wondering about my fiancé would joke about me being pregnant mainly because I don't usually get nauseous like this on my period. I have heard of rare cases where women were pregnant even with a period. We have a little one already and with him I had missed my period which of course prompted me to take a test. After having him my period is just crazy lol but i just thought I'd ask & see if anyone had gone through something like this.