If you have had unprotected sex, or have a condom breaking or been sexually assaulted - you should take the emergency contraceptive pill (the morning after pill). These pills should be taken as soon as possible after unprotetced sex. They can be taken up to 5 days after sex, but it becomes less effective with each day that passes. If taken within 24 hours of unprotected sex they are over 90% effective.
You should get your period within 3 weeks. If it is more than 1 week late, do a pregnancy test.
Nausea and vomiting.