Cramps

Okay so I've been having on and off cramps today... When it started it was very dull and as I walked felt like a muscle or something but my lower back has pain as well... Well I'm following two apps to keep track of my cycle and ovulation... Well the Ovia app says that I ovulated since the 26th of Jan thur the 31th of Jan and as for glow im in my ovulation stages now... I'm confused as in which one to follow but I know my PERIOD isn't due on either app 'til the 21th...so that's still a few aways to go... So could anyone know what this possibly and why I'm feeling this way? Could it be implantation occurring since I'm following the Ovia app or wait and use glow 'til after ovulation?