She should get treated for thrush/Candida infection (the most common type of
yeast infection). If gone untreated or treated poorly, then it
can spread to the rest of the body, which might explain her sores..although I'm not sure that it can cause sores. Not a lot of research has been done for Candida infections.
Either way, it's difficult to spread to males because the male reproductive organs are enclosed. Usually you'll just have irritation.