Foul Smell

After everytime I orgasm and it’s only specifically when I’m on top it’s ever happened! I tried looking online and it says BV but this has been going on for about 2 years now so much so I don’t go on top anymore and it’s my favorite, I tried it again for the first time a couple days ago and it happened again! I also get tested regularly and I don’t have BV or anything of the sort…I want to feel confident again does anyone know Whats going on I need answers