quick question about yeast infections...

I have been involved with a couple of girls and one of them has recently gotten a yeast infection. She says that it could be from me having sex with another girl arodn the same time as her. She is going to the gyno this week and says they will be able to determine if I have had sex with anyone ele besides her and transferred it to her. Is it possible to tell this and how recent did the other girl have to have been. Tweet