A sour milk smell coming from your vagina is most likely a yeast infection.
It might also be accompanies by itching or burning, but the smell is distinctive because it's not very 'smelly' but rather that unusual sour milk kind of smell..
Yeast infections happen because of a LACK of natural bacteria in the vagina, so this allows the growth of yeast to go unchecked. The natural bacteria would usually prevent yeast from growing.
I would suggest visiting your doctor because there are other bacterial infections these symptoms could be hiding, so best to get checked out.
