If you're having sex with someone, who once had chlamydia, but was treated.. can it come back? my boyfriend caught chlamydia from his ex, when she cheated on him. he went to the doctors, got his pills, and was told he'd be fine. now I'm having symptoms such as pain when we have sex, and discharge. I'm worried, could his STI have come back? Or is this just some infection that I could treat with over-the-counter drugs?