What Causes Spotting After Two Days Of Menstruation While On Microgynon?

hey, i recently started taking the contraceptive pill microgynon 30 again after taking a month break. I started on the first day of my period as you should. My period then lasted 9 days which is much longer than usual ( usually only 5 days). It then stopped which i was happy about as i thought it was just due to starting the pill again. Today 2 days after my period stopped i have been experiencing a brown discharge which at first i thought was my period again... it is not very heavy and only seems to come when i am going to the toilet. Another worry is that i did have unprotected sex in the month where i was not on the pill but my partner did not ejaculate and i took a home pregnancy 2 days after my period was due and it was negative.