Birth control and loose stools?

I've been Gynera for more than one year and I never had any problems with it.The thing is that I sometimes(usually monthly) pass some loose stools.I wouldn't call them watery but they're definetely loose and shapeless.I've been wondering if this is something that can affect the pill?Last month I had an episode of diarrhea and needed to take an extra pill so I ended the pill one day earlier than usual.Today I took the pill as usual but one hour and half lately I passed those loose,shapeless stools.Does this affect the pill in any way?Also I'm on my first week of the pill and had sex with my bf 5 days ago.Thanks in advance.