ok, i have battled this many times. i actually found that the nystatin made it worse, and vusion didnt do a thing. it definitely sounds like yeast, and yeast needs specific treatment. i always had the best luck with lotrimin AF. its over the counter. i have also found that overall, less is more. here is what i do, and it works for me. bathe her in plain water with a handful (more if its a full tub) of baking soda in the water. let her sit a while. no soap or shampoo of any kind, and dont rinse. if you can manage to rinse her hair without rinsing her butt, thats fine, but dont worry about it if you cant get her hair, it makes no difference to leave the baking soda in her hair. then let her dry very very very well. put on the lotrimin. if you can pat on triple paste over it, thats fine, but i really prefer to put on the lotrimin alone because i feel like the paste rubs it off. let her have the lotrimin alone for an hour or 3, then load on triple paste. use the lotrimin twice daily, otherwise triple paste. and NO WIPES of any kind. ever. get soft paper towels, bounty makes really soft ones, they are in a pink package. plain water. if you need something extra for the messy diapers, use some vaseline or mineral oil, or you can use california baby calming diaper area spray, its expensive but you only use a touch and it smells great and is all natural oils. use sparingly, any oil/petrol based products will keep her wet, which you dont want (i know some people said to use vaseline, which is fine for every day, i like using it myself, i feel like there are less chemicals and perfumes in it, but not for yeast. the moisture is not your friend when it's yeast). you want to wipe it off well but not irritate her. by the way, i have found something i like better than triple paste, its called pinxave, very hard to find (i found it online). it works awesome on any kind of irritation (not yeast), works overnight, it is a real barrier and not oil based. it is very drying though, so not good on dry skin. not in place of the lotrimin, but maybe in place of the triple paste if you dont like triple paste for some reason.
diet-wise, try to increase her yogurt but decrease her sugar. yeast thrives in wet and in sugar. most yogurt has a lot of sugar, read the labels. you are better off with plain if you can get away with it, if not, maybe put in a little something else, real fruit, or at least cut the fruity yogurt with half plain. best of luck to you.
