*WARNING GRAPHIC PICTURE*What the fuck is this?

I had my baby May 16, got my first period in July, my second period in August and got my IUD inserted August 13th (last day of my period). After I got it inserted I bled all the way to my next period in September. Since my last period I have been having brown almost black discharge and clumps coming out of me. I was suppose to start my period yesterday but instead in my cup I had black blood and clumps in there gross I know.. I slept in the cup last night and this morning nothing except grayish brown discharge . I just went to pee and see if my period started because I started cramping really bad and this came out of me. Could I be having a missed miscarriage or is this normal for the IUD?