Did your menstrual pain started from the month you got mirena inserted? The chance of mirena giving regular pain in the flanks during menstruation is very little unless it has partially perforated the uterus. You can come to know this by imaging technique like X-ray or Sonography. What mekes you think the pain is in the ovary? Or is the pain in the flanks? Any pain appearing along with the onset of menstruation and subsiding when menstruation is over is highly suggestive of Endometriosis. Endometriosis is a condition where the endometrium; i.e. the inner lining of the uterus is present somewhere else in the body. Throughout the cycle, the endometrium is responding to the hormonal changes in the body. It grows in the first half of cycle - up to the egg release and afetr that along with the growth, it starts secreting. This all is for the preparation for expected pregnancy. When the pregnancy does not take place, it undergoes degeneration and is shed off with some blood from the uterus. This is menstruation. If the endometrium is present anywhere else outside the uterine cavity also, it also responds the same way as that of uterine endometrium. Thus it causes pain because of the bleeding in the other organs. Now if endometrium is presend in your ovaries, what we call as ovarian endometriosis or chocolate cyst, it will bleed in the ovaries (or whichever organ it is present outside the uterine cavity) and cause pain. This pain is indeed very agonizing and known to cause after the menstual bleeding stops. From your description of pain, you seem to have such condition which will have to be confirmed by your gynaecologist by cetain investigations. You may have to undergo examination of your abdomen from inside through a telescope. If it turns out yo be endometriosis, depending upon its size, your age, your childbearing history and desire to have further children it can be treated by medicines or surgically.