I need quick answers before I call my Doc ...

Good afternoon, I’ve had an IUD since February of this year; last night I had sex without protection & today while I was at work I had abdominal pain but it wasn’t unbearable nor was it a long time. I went to the restroom & noticed a bloody-like discharge in my underwear but none when I wiped. Could this be normal? Or is it something I need to be worried about?