My penis smells like fish after I had sex. An_253171 posted: Hi, back in April I had sex with a girl and 2 weeks after the sex my penis smelt a lot like fish, so I went to the doctor and got tested for Chlamydia, Gonorrhea and Tritch. I had none. Then the skin started to peel around the head of the penis. I then took medicine for a yeast infection, it did not work.