Are Headache, Uterus Pain And Missed Period Side Effects Of Copper IUD?

I had an copper IUD inserted at the end of January. My last period was very light compare to my last period. Today my period is 2 days late. I have headaches and minor cramp in my uterus. I had very, very light period and not even enough to fill a panty liner. I took a pregnancy test two days ago and it was negative. In 20 years of my period (since 12) I never been late. Last time I spotted I found out I was pregnant with my now 4 year old daughter.