Smell before AF vs. smell before BFP

This is gonna be a little TMI!!

Okay so according to my boyfriend my vag smells really sweet the week before and the few days before my period. AF is "scheduled" for August 22nd so on August 20th I asked him to smell it to see if it was different and he said it was really, really different. He said it wasn't as sweet smelling.

I haven't changed anything in my cleaning down there routine or anything so that's definitely not why. And he's been going down there for four years and it's been the same smell so he's like an expert on it tbh😂😂

I was wondering if anyone else had a smell change like this before you got a BFP.