I have been taking doxycycline for about 5 days now my period should of come between the 5th and 9th. still nothing. should i been worried?

DoxyCanDelayPeriods: Nothing to worry as Doxycycline is known to cause delay in periods.But if you have been having unprotected sex then you do a pregnancy test.Doxy can delay periods from few days to weeks

Birth control pills: Some antibiotics can affect the efficacy of birth control pills. That being said, if your antibiotics started AFTER the expected period, should be irrelevant. Check a pregnancy test.