this post is 4 years old. please pay attention to dates when responding - thanks!
A rash that is not blisterous, pimple-like, or causing discharge is most likely not std, but heat rash from the recent sexual intercourse or friction from the act. A woman's birth control can also cause her to secrete immense amounts of medical discharge that a male may be allergic to, just as a woman can be allergic to a male's semen. Condom latex allergies or allergies to lotions/lubes used can also cause irritation and result in a rash.
Have you all gone for follow up testing to make sure the chlamydia is gone? Its not usually recommended, but since you have some symptoms, it might be a good idea.
That said, it doesn't sound like chlamydia. It could be a fungal infection or even a prostate issue. You should follow up with your doc.
AJ