Does anyone know how long breakthrough bleeding last?

So I have started taking oral contraceptives (Cerelle) like a month ago and I already had my period this month and it finished last week. Exactly a week after my period I got my period again and I found out it's called breakthrough bleeding. I thought it was supposed to end in 2 days but it's day 3 now and I'm still bleeding!!! Has anyone come across this kind of situation?