WHATS GOING ON

HELLO FIRST TIMER HERE... I HAVE MY PERIOD ON EVERY MONTH ON THE 27. I STARTED SPOTTING A WEEK BEFORE MARCH 27TH IT LASTED FOR 3 TO 4 DAYS. WHEN MARCH 27TH CAME I HAD NO PERIOD.I WAS 5 DAYS LATE THEN I STARTED CRAMPING TODAY (4/2/07), THEN SOME BLEEDING STARTED BUT IT'S NOT HEAVY. MY PERIOD USUALLY BE ALOT MORE THEN WHAT ITS DOING. I TOOK A PREGNANCY TEST YESTURDAY BUT IT SAID NEGITIVE I NEED A LIL FEED BACK