Bleeding during sex

So.... I've never bleed during sex, like it wasn't a lot but there's some spots in the bed and after sex a help a towel down there because it was sore and I looked and there was a spot of bright red blood. It made me think, is this from ovulation or implantation, why would I bleed during sex? Again it wasn't heavy at all. Or a lot. What do you guys think.. Also I've been Sooooooo tired lately for a couple weeks now all i can do is sleep and I have no energy at all. And sometimes I get light headed and nauseous. I have a feeling it couldn't be pregnancy because he thinks he cannot have kids.... plus a lot of new acne..