Sorry, I do not know the answer to your question. That question would probably be better answered by your doctor.
I hope you get your answer soon. Us preggo ladies have enough going on already, we surely do not need any other extra drama!
You can ask the pharmascist about over the counter medications. They know which are safe during pregnancy. I would also talk to your Dr. I am lucky enough to never have had a yeast infection, but I hear they are very unpleasant. I hope your all better soon.
It will depend on how far along you are and then you will be able to treat it