My girlfriends vagina has had a really bad stench and it wont go away, yeast infection?

No: No , yeast infection by itself is not associated with foul odor. She needs to see her gyn to rule out other infections.

Not likely: Yeast is not associated with a bad stench. Symptoms of a yeast infection may include: burning, redness & itching of the vulva; burning with urination & vaginal intercourse & a clumpy, white, vaginal discharge with no odor. Sometimes the discharge isn’t apparent. She should see her medical provider.