Every time I have intercourse I have a fishy odor. What does it mean? Are there any over-the-counter treatments? Please help

No OTC treatment. Sometimes disturbances to the natural bacteria in your vagina (douching, irregular bleeding, unprotected sex, etc) can allow abnl bacteria like Gardnerella to overgrow and cause a fishy odor. It's not sexually transmitted, but can be treated w/ Metronidazole (Flagyl)/Clindamycin/Boric Acid. See your GYN for a prescription and be examined for other potential causes. Nothing urgent/dangerous though.
Fishy odor. What you describe is a pretty classic sign of bacterial vaginosis. It requires a prescription of either a gel or an oral antibiotic. You will need to call your gyn.