I need “down there” girl friendship advice..

I need some advice..

One of my best closest friends sometimes smells down there.. she’s told me many times in the past that she often doesn’t wear underwear so there’s not even much of a barrier. There’s been multiple times where she’s gotten up and there’s been a smell (fishy and urine like) that lingered, same with the bathroom. I’ve been to the bathroom after her and I couldn’t believe the smell. I know she showers everyday so I know it’s not that she’s skipping showers. It’s pretty bad to the point where I think she’s gotta know? But also.. why would she not wear underwear or do something about it if she knew right..? I’ve thought about bringing it up to her but I just don’t know how she would take it but I also feel like a horrible friend letting her walking around with that smell.. surely, I’m not the only one who’s noticed. Would you tell her or not? If so, how?