What Causes Delay In Menstruation Other Than Pregnancy?

My period is late by 1 day and second today I've been having symptoms of period and tender breast .today I thought my period came but only blood on the tissue paper when I wipe also some in my urine but no period on my pad I did a pregnancy test 3 days ago it was negative I've never had this problem before im having slight cramping but not my normal cramps I try to be careful when I have sex so what's going on