K.G.
Hi. Both my daughter (now 3 1/2) and son (4 months) have had thrush. My son had had it for six weeks starting when he was just three weeks old and we were treating it with nystatin when the doctor suggested I also add 1/16 of a teaspoon of acidopholus to one of his bottles daily (he wouldn't breastfeed so I was pumping). This did the trick. There are other probiotics besides acidopholus and both my kids take one daily, which has really helped to strenghten their immune systems.
Hope this helps. Good luck.