Mirena symptoms?

I got my iud inserted about 2 months ago.  The spotting has stopped and I've had sex.   I know your period is supposed to stop but It's about 8 days late for my (regular period) and I'm cramping like crazy, one was like someone was pinching my ovary. It was awful and lasted all night.  Plus my nipples are so sore.   Is this normal? Are these because it's the normal time for my period?