A lesion that bleeds after sex is very unlikely to be herpes or any other STD. In fact, I have never seen or heard of a bleeding herpes lesion. Further, since it happens every time you have sex, it would have to mean you have a continuous, non-healing herpes lesion--and there is no such thing.
I have never seen genital warts cause this sort of problem either. However, I can imagine that a wart at just the wrong place might be injured, simply because it's a prominent piece of tissue that might be rubbed a lot during sex. On the other hand, in that case a health care provider ought to be able to see the warts at or next to the traumatized area.
I hope this helps. Best wishes-- HHH, MD