My son had thrush when he was new and we used grapefruit seed extract (diluted!!!) on his bum and in the laundry with his cloth diapers. This was in addition to a prescription, we did nystatin first, and turns out he needed a stronger one (I think it was flucanazol?). His pediatrician mentioned that she will often start at the stronger prescription, as she's noticing that the nystatin and other "softer" versions aren't even effective anymore.