Hey there, Lele. Welcome to the boards.
Next time you post, could you not capitalize every word, please? It makes it very difficult to read what you've written. Thanks!
We won't engage with pregnancy scares here, so besides directing you to take a pregnancy test if you have a concern about that (though it'd be about a couple weeks too soon for that just now, as even when pregnancy does happen, it takes longer than a few days to happen, and longer still to produce the hormone a test reads for), that's not a discussion we're going to have.
But there may be a bunch of reasons you feel weird in your stomach or otherwise. For instance, if you were drunk, then it's possible the sex you engaged in wasn't, or wasn't very, consensual, and that can certainly make a person feel nauseated, because that's not okay. You don't say anything about what you actually wanted here, and if you wanted to have sex with whomever you had sex with. If you don't know if you used contraception or safer sex or not that certainly can also cause you to be very worried, and it's common for worry and stress to result in stomach upset.
Where would you like to take this discussion from here?