Is Cerazette Mini Pill Causing Diarrhea?

Hi, my last period was 20th March or thereabouts, I'm on Cerazette mini pill, I've had diarrhoea at the weekend and this morning been sick after eating. I did a pregnancy test last week to be on the safe side, it was negative. Unfortunately for me, I'm related to a girl who went full term without knowing she was pregnant, thoughts please??? Many thanks. Lindsay