I'm sorry I don't have a solution to your question, but something similar has happened with Molly , she's always been ok in the bath, but when we came back from our holidays a few weeks ago , I picked her from the kennels and they said they had bathed her the previous day, but she was still a bit wiffy so I gave her another bath.
She started this terrible crying and moaning, it was really distressing and very unusual, I wondered if she had had a bad experience at the kennels whilst being bathed
But she soon bounced back to her normal self, hope Tilly does too!