help what is this fishy smell?!

I recently had sex this weekend with two different guys a day apart after it having sex for 2 months during which my vagina was balanced and was fine. After sex with the first guy everything seemed normal I liked his scent on me it matched it wasn't anything weird. SECOND GUY however was not like that. I couldn't bring myself to have sex with him and had to stop because of how bad the stench was. Second day I shower and I come home and I have the same scent too and it's been three days I shower every morning and night I change my underwear frequently and the smell still won't go away. My discharge is normal and clear I'm fertile rn. What could it be???