Does the effectivness of the Merina IUD/IUC dwindle towards expiration?

My IUD is 4 1/2 years old - expires at 5 years. I'm getting concerned because I've been feeling queasy off and on for a few days now and my period has only been light spotting - I don't even need a panty liner, it is so light. No pain in my - which is really weird because when I get my period my s are usually one size bigger than normal. This is the first time I've had a period without sore in years. What could be going on? I know you all aren't doctors, but I don't have insurance and am just curious fishing for opinions.