Mirena cramping

I'm going to see my doctor regardless because something feels off but i have been experiencing some rather painful, low cramping these last two days. I have had the Mirena IUD for about a month now and this is the time I should be getting my period but I haven't yet. I took a pregnancy test because I was raped three days after starting it, and so it wasn't effective yet but that's all clear. it's just really sporadic and painful and I'm
wondering if this is normal adjustment to the IUD or if something is wrong.