Implantation pains?

My birth control pill is one where you stop taking it for a week to allow your period to come, well I forgot to take my first pill of the next packet, did the deed then realised the next morning took my pill from the day before and went on with my day.
Now since then I've been having crampy pains and they hurt!!

I doubt missing one pill would get you preggo. Esp the first one. That's not your peak ovulation time as far as I understand.