What Causes Vaginal Bleeding And Pain After An Intercourse?

A few hours after having sex, I began to experience pain, somewhat of cramping yet kind of like a tear at the same time. We noticed I had bled a little during sex and now when I wipe there is blood on the tissue, enough to warrant wearing a thin pad. Could he have hit my IUD & caused it to move? Should I be concerned? Fyi, i did just end my cycle less than a week. Its not uncommon for me to show signs of blood within days following then end of my cycle but to actually begin bleeding & be in pain.... not what im used to.