Why it could hurt to have a bowel movement

I asked my doctor why does it feel like a baby is coming down the shoot. Her reply was that maybe I had internal hemmorhoids. I did not realize this and used a suppository for a week and it worked. My pain before a BM was decreased day by day. I am 12 weeks post op and experiencing after sex bleeding. I know its not do to dryness so when I figure this one out I will let everyone know.