Birth control,but feeling Nauseous

So i've been on the pill now for a good 6 months & I haven't missed a day i take them perfect every single day,so a month ago i left to Canada for almost a week & when i came back me & my boyfriend really got into it but he cummed inside of me a lot but i was on my period ( yes i know some may think it's gross sorry) but my period was ending now a couple days ago i'm noticing that i'm getting nauseous & i feel light headed & ot comes & goes spletimes the smell of food makes me nauseous or if i lay on my stomach.. What do you think it can be ? Stomach Virus perhaps? Also i got my period normally this month as well.. (Also the canada trip was about a month ago meaning he cummed imside of me a month ago) Soo help