Wipes & 'sitz' baths
It is hard for young children
to master the coordination for cleaning well--it requires pretty sophisticated motor control! premoistened "diaper
" wipes do a better job cleansing than tissue and are much gentler. I'd also suggest a brief "sitz bath
"--just water with no soap/bubble bath--a couple times a day.
This will keep her clean which is key, and if necessary, a zinc-oxide based cream can help.