I had period for 1day.next day the bleeding was very light only spotting. my periods are regular always but last for 2days.my menstrual cycle ranges from 27-30 days.i did pregnancy test but it was negative. so why period lasted for 1 day?

It happens sometimes: Many women have occasional variation of their mucus discharge, some spotting between periods, a heavier period, a lighter period, a longer or shorter period, or even a missed period. Having one or two of these symptoms doesn’t necessarily mean there is a medical problem, but a visit to one’s primary care or Ob-Gyn doctor is a good idea if symptoms are persistent, recurring, or worrisome.