is something wrong?

yesterday, my period seemed to have started. very light spotting that USUALLY quickly becomes heavy bleeding. i got horrific cramps as well, which isn't uncommon for me, but still really bad. however, my period is nada. like there is nothing now. and in extremely bloated. like there is a good pressure on my stomach from it. it not comfortable. and my breasts are extremely sore, to the point a bra hurts my nipples. im also extremely emotional and i hate it. I shouldn't be pregnant as I have an IUD. what is happening?! help!!