Skyla IUD

I'm 19 years old. I just had the IUD I inserted last Tuesday and I was supposed to Start my period right after. Well I did but now it's going on 8 days and I'm still bleeding. Has anyone else had this issue? If so how long did you bleed or spot. It's dark enough to be considered period but sometimes it's light enough be to considered spotting. So I don't really know what it is?? Should I call my Gyno. My period is never this long.