DIAGNOSED WITH ABNORMAL UTERINE BLEEDING AND FLUID IN MY OVARY! HAVE TO GO BE SEEN AGAIN! WHAT COULD BE WRONG?

i went to the er because i have been bleeding every other week for the past 6 weeks! they did blood work and gave me 2 ultrsounds! my diagnosis was abnormal uterine bleeding and fluid in one of my ovaries! i have been having severe abdominal pains! the er doctor told me i need to be seen right away by my obgyn and prescribed me provera! what could be wrong? could cancer be a possibility?