I HAD MY PERIOD AUGUST 23RD AND AS USUAL MY CYCLES ARE LIKE CLOCK WORK, IT LASTED UNTIL THE 27TH. I HAD SEX ON THE 29TH, BUT THEN NOTICED FOUR DAYS LATER ON THE 2ND, I WAS HAVING SOME SPOTTING. THE SPOTTING LAST FOR THAT ENTIRE DAY, AND THE NEXT DAY WAS GONE. BREAST HAVE BEEN FEELING A LITTLE FUNNY BUT NOT SORE, EXPERIENCING FATIGUE IN A MAJOR WAY, AND HAVE LOWER BACK PAINS. NO NAUSEA.. WHAT COULD THIS BE?