What Is The Heavy Bleeding And Cramps After Having Sex?

9 weeks postpartum, had a vaginal delivery with a few stitches and no episiotomy. I stopped bleeding around 7 weeks and started birth control pills a week ago. I had sexual intercourse a week ago (we used a lubricated condom), and no bleeding. This week however, had sexual intercourse again (sans condom or lubricant, I felt lubricated enough) and immediately started having cramps and bleeding very red, heavy, watery blood flow. No pain other than cramps, no blood clots, and no foul smell. Should I go in for an internal exam? Or is this normal or due to another factor?