If this is happening about once a week, take a note as to what she ate in the 24 hrs prior. Try to make sure she is not have anything with high fructose corn syrup, it is many things. If she drinks apple juice make sure it is organic. I think if it was a UTI, it would be an everyday thing. She could be sensitive to the chlorine in the toilet paper. Look for chlorine free tp from 7th generation or whole foods has there brand. Not as soft as conventional, but the idea is to pat. Her undies should be 100% cotton and should be washed with fragrant free detergent, I like 7th generation, borax or melaleuca. Also, make sure it is not after using bubble baths, soaps can be very harsh with chemicals such as sodium lauryl sulfate, # food coloring, lanolin, parabens, synthetics, and petroleum. If these are in it I pass on them, I would rather pay the extra money and use Baby Avalon, Aubrey, or California Baby. www.luckyvitamin.com sometimes has these products for less. I hope this helps. www.mybiopro.com/claudia13