Just early bleeding. I assume you have not skipped any pills or changed the time you take them. Occasionally, it's not uncommon to begin slightly earlier. The discharge is just plain old blood...most are accustomed to bright or dark red; however, there can be times it's older and remember the lining is being shed as well.
I would not concern yourself unless it happened for several months consistently. There are times you can even have break-through bleeding early on.
Despite being on the pill, there may still be months where you get heavier cramps which require Ibuprofen or Tylenol. If you are concerned be certain to contact the prescriber.
sera300
Posted: 23 Sep 23:48