For the last couple days I've been having pains in my stomach. I have had diarria and a little bit light headed. I've been reall sleepy. Could I be pregnant what should I do??

The Mirena is a good source of birth control, but like all birth control, it is still not 100% effective, every time you have sex (im assuming you did) you risk prgnancy. So yes, you could be pregnant and you should test.