Early period on xulane patch?

I’ve been on the Xulane patch for over a year now and this has never happened to me before. I’m currently on the third week (June 25) and my change day is Sunday. I noticed some dark brown discharge 5 days before my period should start and I’m getting cramps earlier than usual. If it helps at all I’ve had sex 2 times over the past 3 weeks. Why am I getting an early period all of the sudden?