Hi ! Good morning. I am Dr Shareef answering your query. Even if you are using mirena, it is not a hundred percent guarantee against pregnancy. I would suggest you to go for a serum HCG estimation and an ultrasound of the abdomen if need be and if advised by your gynaecologist to confirm/exclude a pregnancy. At the same time, I may add that some ladies who are intolerant to mirena do experience such symptoms. So you have to get yourself investigated before deciding on anything. I hope this information would help you in discussing with your family physician/treating doctor in planning your treatment. Thanks for using the health care magic forum for your query on health. Wishing you an early recovery. Dr Shareef.