Can yeast infections cause the vagina to develop a foul smell?

Not exactly: Technically a true vaginal yeast infection will cause a thick cottage cheese itchy vaginal discharge with no odor. In real life women with yeast infections often complain about odor. If there is a fishy odor i suspect it is not yeast but actually bacterial vaginosis. Either way a visit to the obgyn is needed to determine the cause and help yor get better.