Sick need help

For the past few days I’ve been feeling horribly sick and no symptoms besides nausea and pressure in head. I feel just as bad as I would with something like the flu. My periods are always a few days later than last so my period could come any second. I’m wondering if that could be it or if I’m sick. Im praying to god it’s not pregnancy because my anxiety is horrible, but I highly doubt it isn’t because the fact we use condoms properly and never finish inside me. What is up?