I skipped my placebo pills...but I'm still bleeding. Why?

I'm on Mono-Linyah and have been for almost a year now. Up until about two months ago, I always took my placebo pills, but then, I started skipping them and just starting a new pack. This would allow me to skip my period...until this month, when it didn't work. I don't remember the exact day I was supposed to start the placebo pills, but it was about two weeks ago. Since then, I have been spotting/lightly bleeding.

What caused this? Should I take a break from the pills until I stop bleeding?

Also, I did take one dose late during the week before I was supposed to start the placebo pills, but it was only by about 3-4 hours. I have experienced spotting after taking a pill late in the past, but it never lasted this long.