birth control

so recently i started taking birth control that is safe to use while breastfeeding. (sorry if this is a stupid question/ post) the birth control is called errin, not sure if anyone else has tried it. anyways the past few days it look like i got my period . its been super heavy and i've had a bit of cramping. is this normal? i didn't think i'd have to be changing my pad this often and (tmi) but sometimes it feels like its just pouring out when im walking or doing something.