Bleeding after sex?

The last few times my boyfriend and I have had sex it feels like he’s bigger, or I’m smaller. It just feels like he’s stretching me more than before. We just had sex about 40 mins ago and after he left to go back to work I went to the bathroom and noticed a tiny amount of blood, not bleeding, just blood. Could he have accidentally tested something? I don’t think I was wet enough cause I was impatient, and now that he’s gone I wish he was here lol