Bleeding after sex, ttc

So I had sex this morning and I’m ttc and so after I put a pillow under me and my knees to my chest for 15mins. After 15mins I wiped myself and noticed blood, now after 3 hours there is no blood there. I’m also taking 300mg of Vitex and I’m going up to 600mg today, tomorrow starts my ‘fertile window’.

Why did I bleed? I wasn’t in pain or anything.... it felt good because this was the first time we had sex in two weeks.