You wouldn't be feeling sick due to pregnancy 3 days after. Until implantation occurs symptoms will not occur, and the soonest implantation happens is usually around 6 DPO. More than likely you feel sick because of a bug or nerves.
have you taken a test? also since this happened saturday you might be close to ovulation, im not sure bc i dont know your cycles, but if you miss this upcoming period you NEED TO TEST!!! if you want you can test 2 to 3 weeks from saturday and it should give you an accurate answer.