This happened to me earlier this week. my partner developed a blister on his shaft and treated it with diflucan (which is for getting rid of yeast infections) so when i began to get the same symptoms i tried treating it with monostat and began having reddish brown discharge two days into the treatment. when i went to the doctor, she told me i had a serious UTI and if i took cypro it would go away. However after doing some research, i found that yeast does not show up on tests doctors do if you have been using monostat. my doctor also told me that using monostat changes the PH inside you and can really jack with your body if you do not have a yeast infection. having this said, i would tell you to get her into the doctor and see if it is caused by a UTI and work from there. in my case, i had both and had to suffer through the yeast infection until i could get the uti taken care of
I haven't ever heard of anyone reacting to monistat in that way. Honestly sounds like she is starting her period. However, she should always see her doctor first if she believes she has a yeast infection, unless she has had yeast infections in the past and is very familiar with the symtoms. There are many other things that can cause white discharge and itching, and testing should be done to determine the cause.