Last friday i had the Mirena inserted and although the insertion was a bit uncomfortable all in all its been ok, but a couple of days ago i started getting headaches, dizzy spells and light headed. Could this be due to the Mirena, i also realized that my pharmacy gave me Effexor XR and i was taking venaflaxyn. I know that its the generic version of Effexor but it should work the same.. right?? I have been on venaflaxin for 3 weeks now so it shouldnt be symptoms of it, could it?