why would my vagina smell like garbage if i dont use tampons?

recently my discharge has been milky white and smelled like trash juice. i THOUGHT IT WAS BV BUT I WAS TESTED FOR BV YEAST AND TRICH AND ALL 3 CAME BACK NEGATIVE. online it said the reason it would smell like that is because a tampon got lost up there and thats it. however, i don't use tampons and have never used one. so what other reason could there be. the only one i could find online was the tampon one. i was STD tested january 6, all negative, haven't been with anyone since.