side effects....

I know I constantly ask with the nuvaring, but I'm not close to my mom. Anyways I'm 18. I recently got on birth control, the ring, in February. Since then I've started having painful experiences with my period. This is the first form of birth control I've taken. But before the BC I've had little to no pain with my period. Is it possible that the form of BC just changes the period, if so how long will it be like this? Any other person feels this way?