I would think it is stress related. I had the same IUD and I actually had more regular cycles than ever, with them being exactly 28 days. Once I had it removed I was all over the place again with shorter and then longer cycles but at the same time I was stressed because we were trying to get pregnant. So I think it was stress related for me, too. They say it is rare but possible to get pregnant on the IUD so I would check just incase. Maybe take a pregnancy test. Have you done that?
Yeah i did it this morning and it came out negative...