Bleeding and clots after sex

Had sex last night and no bleeding afterwards. Woke up this morning and had some spotting on my pantiliner. Went to the bathroom and this plopped out along with some bright red blood. I normally wouldn't be worried but this clot was borderline if not was bigger than a quarter. I guess I'm just looking for a little reassurance this has happened to others before call my Dr

Also, I'm in my fertile window. Period ended about a week ago

Posting it here along in the sex group too