What Is Causing My Irregular Menstruation?

I am 19 years old, I had my period from October 2nd to October 8th, then I had it again from October 21st and I still have it. My first period of this month was a normal flow, and this one is super heavy, I have to change my super tampon every hour. I am also experiencing some cramps, and tender breasts. I have never had my period two times in one month, and I have never had a super heavy flow. I also rarely get cramps, and I usually don't get tender breasts with my menstrual cycle. I am looking for some insight of what could be going on?