Is she having any other issues with her feet? Not overly sensitive to anything else, socks etc?

Is she ok in the shower, or not liking that either, could you maybe wash her hair in the sink, make pretend she's at the hairdressers or something, let her help do everyones hair in the sink and see if she lets you do it afterwards?

Maybe it is just a phase, i hope so for your sake.

Prob no help but good luck!