Copper IUD and Newly Happening Cramping

I've had my copper IUD (Flexi-T 300) for a year and it's been fairly smooth sailing, I had no issues with insertion and my periods didn't change right away, but lately things have been getting a little funky. Last month my period wasn't necessarily late but it was incredibly light for a few days and then very heavy for two. I'm due for my period in 5 days and I'm having some period-like cramping, nothing else. Could this be regular effects of the copper IUD finally taking place? I highly doubt I'm pregnant but, of course, am always worried about that possibility. Does anyone else experience this?