My Last Period Was Weird And Very Painful. I've Had

my last period was weird and very painful. I've had the copper IUD for almost a year and the strings are the lowest they have ever been. My period is always the same and this time I bled heavy for 2 days and then was only spotting for the last 7 days. I also had a lot of pain and cramping that was similar to when the IUD was first placed. What could cause this? Any chance of pregnancy?