Prenatal vitamin

Guys, i’ve been taking new prenatal vitamin since a month ago (Nature Made prenatal vitamin). I didnt have period on September. I’ve got my period on October 13th till today. It was stop on 20th morning and started again. It was always black and light flow, but today it gets red and got cramp in my lower tummy, just like my first day period. My breast hurts since a week ago. Do you think it’s hormonal because my new prenatal vitamin? Or something else? Will go to the doctor this monday, but really need insight first from you all. Thank you