I am on Aviane birth control, the 28 day pack, for one month and now two weeks and I had unprotected sex last week.  Is there a chance I could get pregnant?  I've been having lower abdominal pain, feeling like I would be getting my period, but it's too early.

If you have been taking your oral contraceptives regularly for 6 weeks, you are 99% protected from pregnancy.  However your abdominal pain may be due to a STI or from a urinary tract infection.  Schedule an appointment with your health care provider for evaluation, and remember to practice safe sex.