I can completely understand how scary the "unknown" factor in a situation like this can be. Is there any way you talk to the guy to find out exactly what did happen? Knowing might help put your mind at ease.

You're right that mixing sex with alcohol is usually a "bad idea" because alcohol can diminish your ability to make sound judgments, making it more likely that you will have unprotected sex or that, in your state, you will use a condom incorrectly. However, if you were passed out, you could not have consented to sex--protected or unprotected. Consent laws are complicated and vary from state to state, but it is essentially against the law to have sex with someone who is incapacitated. There may be some recourse there, if you feel that is something you wish to pursue.

But back to the issue at hand. Seems like you're feeling pretty scared and helpless right now. Taking action may help you diminish your anxiety and help you to feel some measure of control over the situation. There are several things you might want to try. Emergency contraception is available for situations like these, but according to officials at Planned Parenthood, EC is most effective up to 72 hours after a sexual encounter. It may be taken up to 122 hours after an encounter, though.

At the very least, you may want to take a pregnancy test and a test for sexually transmitted infections, both of which can be administered by your local department of health, community health clinic or Planned Parenthood clinic. Planned Parenthood offers confidential testing for sexually transmitted infections and pregnancy, as well as emergency contraception. Many clinics offer sliding-scale fees. You can find the clinic nearest you by calling 1-800-230-PLAN. You can also search for clinics by area code at Teenwire's Clinic Connections page. To find other health care providers in your area who provide EC, you can call 1-888-NOT-2-LATE.

Here's a Teenwire article on sex and alcohol you may find helpful as well.