I had what I call "pelvic" stabbing for about 5 months after I had Mirena removed. It seemed random and not based on my cycle. Since then it hasn't come back, except the day I ovulate. Before Mirena I never knew when I was ovulating, but now it is painful. Hopefully your cramps will iron out soon.
BTW I am also starting school again tomorrow. I've SO missed the mindless paperwork and meetings all summer!