What Causes Severe Pain In Hip After Inserting Mirena IUD?

HI, I had the mirena iud put in a few months ago. For the most part, I love having it. But I have now experienced very severe pain in my right hip. It has only happened 3 times (right now being the third). It has always happened at night, feels like it is unbearable, but by morning it always goes away. Is this "normal" cramping? I've never had cramps before so I don't know if maybe this is a typical when getting off pill and on to iud. But the pain is so severe (pain meds don't help) I am worried something is wrong. How do I find out if this is a "normal" side effect or if I should go to the doctor?