Every time I have sex with my boyfriend, I start to smell really bad. Like terrible. He doesn’t cum in me & I was on the patch.

The smell doesn’t go away by itself. I use flagyl/Metronidazole but I don’t want to use it constantly then it might stop working.

To prove its him, I took the flagyl then didn’t have sex for over a week. The smell came back the very next day after intercourse.

I’m not a smelly person on my own or in general. I’m assuming he’s not cheating but what could it be and what can we do to fix it?

Update:

He doesn’t smell, we’re both very hygienic. Clear of STD/STIs; we got tested together.