Call her doctor, he or she needs to be aware of this. Also, switch diapers in the meantime, wipe her from front to back when changing her. It could be a yeast infection, they can get pretty nasty looking and be painful, and obviously something is seriously wrong with your poor daughter, but her doctor will need to see her and make the diagnosis and prescribe something. Antibiotics cause yeast infections so they have experience in this. Another mama also suggested she may be constipated, which could be blocking her urine flow, another strong possibility.