Sweat Rash?

My mother has a rash under her breasts (in the fold). She's had it several months, she did see the doctor and he just told her to use talc, which she was already doing. However, it has not got any better. I was wondering, if Apple Cider Vinegar could be used to treat it? It could be linked to yeast growth right? Any advice on this would be very much appreciated. Tweet