has she slipped or something in the bath? Maybe had nappy rash which has hurt her?

Ashton loves his baths and showers, though the last month he has shown a preference for shower Loves the water on his head which is very different from the others.

I wouldn't push it, things like this don't get better if you force her in the shower/bath. Sponge baths for now is what I would recommend with trying the shower or bath once a week until she is over her little fear.