You could have an yeast infection there. I know this sounds weird but I have seen it happen. I am a medical assistant. It is most likely a heat rash. I would try rubbing some benadryl cream on it. If it don't go away go see the doctor, and see what he/she says. You may be able to call the doctor and you may be able to put an over the counter cream on it to take care of it. Good luck.
