Implantation? Something else?

It could be caused by the pill or just your hormones changing as they do throughout life, but may also be pregnancy. Ive had this happen once and it had never happened before so i was concerned but my period came I wanna say 'bout a week later and then the same thing happened a week after that period but I wasn't prego..So i would just wait it out see what happens and if nothing then test.