UID and pain after sex

I've had my Mirena IUD for 8 months now and LOVE IT. I recently had rough sex with my boyfriend and it didn't seem any rougher than usual. After the sex, we went to sleep, and I woke up two hours later with MAJOR cramps. I was moaning in pain for a good half an hour and could not go to sleep. I took an ibuprofen and finally fell back asleep and have not been in any pain since. Any idea if it was an IUD issue or maybe just a one time thing because of rough sex. With my IUD I haven't had a period since it was inserted, but I know period cramps and it was not my normal period cramps that I had before my IUD. Any ideas?