Ay, 4 days delayed is usually still within normal range, kaya hindi pa ako mag-aalala, pero honestly if you're worried, better to do a pregnancy test na lang or check with your OB para sure na, na-stress din ako dati over delays na normal lang pala! When did you last have intercourse, and is your cycle usually regular? Sometimes ang stress, diet changes, or even exercise intensity can push our period a few days, kaya it happens to a lot of us din.