I got my period on 9th sep it's over almost after 5-7 days but little bleeding continued for 4 days and then again on 5th day I got my period and it's been 16 days it's still here .I had just tried sex on 6th or 7th july with protection .after 3 weeks done 3 times pregnancy test .all was negative .then got my period on 21st august before that my period was on 28th June .and this month 9th sept and it's still bleeding .my periods are always irregular .what should I do?