hello,,,iam dr xxxx..
your symptoms does not seem to be due to mirena
..if you are scared of being pregnant get a urine pregnancy
test done with early morning sample..
did you had any previous surgery(prev.surgeries, pregnancy,caeserian can cause adhesions or mild infection (pid)in some patients causing pain abdomen etc)
how ever its been 4 yrs of insertion of mirena(usual life 5yrs)...get it checked.its position ,functioning ,usgbdomen (if required)..removal and reinsertion of new mirena or any alternate contraceptives depending on yoru need by a gynaecologist... nothing to worry or panic
you will be fine soon..bye