Oh and yes, that does sound like a migraine. If you have sensitivity to sound, or especially light, then I'm almost certain that's what it is.
Mirena and all IUDs change your hormone levels. Migraines are often caused by changes in hormones, that's why they're more common in women, especially around menstruation. Your doctor should have warned you of this and I would definitely go see him because it may not go away.
This is one of Mirena's many warnings:
"Mirena should be used with caution in patients who have: Migraine, focal migraine with asymmetrical visual loss or other symptoms indicating transient cerebral ischemia"
It warns patients who have migraines because it increases the risk of having a migraine so that even someone who does not typically have migraines may be at an increased risk of having one.