Have had same sex partner for partner for past 3years, fishy odor only after sex no type of didcharge what can it be???

Possibly BV: Bacterial Vaginosis (BV) is a vaginal infection that is not sexually transmitted. It often causes a fishy vaginal odor, usually worse after sexual intercourse. A milky discharge is common, but not necessary. BV does not typically cause itching/burning. Douching, antibiotics, and other causes lead to change in normal vaginal flora. See ur dr for an easy test to confirm and treat if positive.

Bacterial vaginosis: Bacterial vaginosis is where the normal bacterial which live in the vaginal grow too much and cause a fishy odor and usually a discharge. It is not a disease but can be treated if it persists. It tends to be more prominent after sex and during menses. See your doctor if it persists.