How do you tell a friend?

So I have this friend who has a very smelly private area. We used to always get dressed together and would take turns using the bathroom while the other does makeup. So basically I stopped and would not go in the bathroom while she was in there because her girly gives off this foul smell. I used to think "maybe she's on her period" but it smelled ALL THE TIME! When Christmas came around, 1 of our other friends who noticed the smell bought her alot of feminine products and I kinda seen that it pissed her off a little. I really want to tell her but I don't know how without hurting her feelings. I do want to come off as a bad friend to her, but at the same time I think I'm being a bad friend by not telling her. She's a sweet girl and her feelings are easily hurt, but I wouldn't want her to get embarrassed by a guy telling her that and lower her confidence. So I'm really asking, how do you tell your friend that her kitty has a smell in the most positive way? Or do I just not tell her at all? I'm really stuck 😕