17 year old PREGNANCY SCARE

I pasted about this earlier but I got very drunk Friday and this guy took advantage of me. I thought I got my period, but when I changed my tampon earlier in the day the blood was brown, and just now I changed it and it was barley red. So I stuck my finger up my vagina and nothing was on it... I need help! AM I PREGNANT?? WHAT DO I DO?? WHEN DO I NEED TO TAKE THE TEST?