it is possible that u could be as u wld of been ovulating around when u had sex,u can do a test a few days before ur period is due or wait to see if ur late then do one x
The bleeding could have been from ovulation soon about to happen. I have that sometimes as well. It could also be a little breakthrough bleeding until your period comes. You can only really accuratly test when your period is due. You can try an early response test but I wouldn't do one (even if it says 6 days sooner) until 2 days before your period is due. Use your first morning urine for the most accurate results. You may have gotten the stomach virus and that is why you were throwing up. Good luck.
its possible that you are pregnant anytime that you have unprotected sex or contraceptives fail...especially with the symptoms you are describing. although typically morning sickness and nausea don't start until around 6 weeks. is it possible you are just sick?
the most accurate time to test would be after you miss your period. but you can take a test (i think) 2 weeks after you think you may have gotten pregnant. someone can correct me if im wrong about that. but i personally would wait until after you miss your period.
also if you dont want to become pregnant i would suggest you get on birth control...you can get it for free at health clinics or planned parenthood. if nothing else i highly suggest condoms & spermicide.