What Does Heavy Bleeding With Nausea, Cramps And Tender Breasts After Intercourse Mean ?

hi.. i am 23 years old.. i have regular monthly periods.. i had intercourse with my boyfriend last dec. 10, my usual period is every 22nd of every month. the week when im due for my period, i feel something different, im having sleepless nights, nauseated and sometimes vomit, i have mild cramps, tender breasts.. i had pregnancy test at home and it came out negative, the next day i had heavy bleeding that lasted for two days only.. what does it mean?? thanks..