Does anyone know why this is happening?

I had a baby July 1st. My doctor informed me to take my birth control the second Sunday following birth. I stopped bleeding completely after two weeks. When i started taking the pill a week later i started bleeding and cramping like it was my period. That was two weeks before my period would of been due with the pill. I take a birth control called Jolivette. So is this normal? Why would i have a period in the middle of my cycle? Anyone else have this happen? Beings as i am cramping and passing blood clots do you think this is my period or bleeding from having the baby yet? Thanks!