What causes a stong vaginal smell sometimes

when having sex sometimes times the smell is stronger coming from the woman why is this and I notice the smell when I pee it aint always like this just for a certain 4 or 5 days every month or two

you need to wash that thing out sometimes... or you've got something you need checked out with a doc

I read in this book that it's normal and natural for a girl to have a musty odor. Not a strong one, but an is present. if the odor is strong, and yellowish muscous appears with it and it starts to itch then thats when you need to get it checked out. but I think you're fine.

Pheromones. Also, the woman is secreting more than the man.