I had sex on monday. one day before my expected my period. today is thursday and i'm two days late. last night i had abdominal cramps and could smell blood but this morning i didn't bleed. i'm worried.

You are ok: if you had unprotected sex a day before your expected period, that mean you are far away from your ovulation. so you are safe. the delay period and blood are expected, you are still safe. it is safer if you practice safe sex, and you keep your self protected, there is a lot of medical condition you should worry about beside pregnancy.

Be patient: It would be very unlikely that you could get pregnant at this point in your cycle. Be patient. If your period has not come in one week, take a home pregnancy test. I hope this helps!