What Causes Light Period And Vaginal Spotting After Intercourse?

hi, I have 2 kids so i did family planning operation. It already 4 yr. now days am facing problem in my monthly period problem . Its in same date every month but only spotting kind (for 10,12 days) . then again start the same date of the month . i don't know why it clotted. also this month i noticed after intercourse immediately i saw little bleeding not painful then stopped. why its is happened? Is there any problem. am 35yr old.