Yes yeast infections can cause a woman's vulva to sore. Control on your diet that contain yeast and molds.
Yes, yeast bacteria can cause sore to the area for which it has infected. Try the monostat cream and if that doesn't work you will need to go on an antibiotic cream ordered by your Dr.
I am having a similar problem. I took antibiotics for my tooth and then noticed later that I had a yeast infection and also got sores on my outer lip area.
So I figured out what it was, I was allergic to the vulvar itch cream. It was way too strong and it tore my skin up!as soon as I stopped applying it it cleared right up!