Vagina Scent/Smell

So my next period is happening in a few days and I’ve noticed a scent going on down there. And it’s not foul nor bad smelling! It’s more of a sour scent actually. And i want to know if that’s normal? Plus my discharge is low. I mean really low. It’s not frequent enough to keep happening unless if I’m ovulating, horny(srry for the tmi), right before my period( mostly I notice discharge happening before my period or a few days before it starts) , or getting turned on. Again sorry for the tmi. So since I noticed that I have a sour scent is that considered okay? Because I know the vagina is an acidic organ and it’ll create its own natural smell and every women is different, I just wanted to know? When I notice it wasn’t that strong either. I would only notice the smell if my legs was slightly spread out, if I’m standing in a particular area for to smell it or I’m getting in the shower. So the scent is not unpleasant, bad or foul, my discharge is not ongoing and the consistency of it is liquid/stretchy smooth idk. One more thing, when I did smell it, my discharge left a stain on my underwear and the color was white with a small tint of yellow? Is that also normal?