yes, its quite common with mirena. If you check back on the last couple of pages of this forum you will see that many of us had dizziness or lightheadedness included in our lists of symptoms. to see all the officially known side effects (though there appears to be even more effects than is listed) go to:-
the best way to stop the dizziness etc is to get the mirena out as soon as possible, before you side effects get even worse. Good luck to you, hope you begin to feel better very soon:) x