My baby boy had same rash what I used was rising powder it really helped since then the rash has not come back, and I bought a bigger size diaper, like if she is using size 2 then buy size 3
I dnt advise using powder on bumbums.pls use eith sudocreme or baby tribotan and always air her bumbum pls whene u r at home dnt wear her diaper.u can put a facetowel on ur laps when carrying her