18 weeks- spotted a bit and passed a lentil sized blood clot

I emailed my doc but I’m going to be stressing all night over this and wanted to know if anyone has had anything similar? This is my third pregnancy and I never had any spotting with my other two or with this baby until now. It wasn’t a lot of blood. Only when I wiped here and there for a few hours and just saw a lentil sized blood clot. Blood and clot were both red so fresh blood. I did have sex with my husband at around 5 this morning but didn’t have any spotting until the evening so about 12 hours later? Could it still be from that? TMI but I have also been constipated so is it possible the bleeding could be from straining? I’m trying to avoid google because it will only make me worry worse. Thanks for reading this, from a worried mama.