Golly! I just took a deep breath for you LOL

Im sure you have already tried absolutely EVERYTHING with her knowing the awesome Mum that you are, you said she calmed down whilst in the shower? Maybe you could put her in the bath for half an hour? Its the only thing that calms Archie down no matter what. I just let him stay in there playing til he asks to get out, sometimes he will be in there close to an hour.

Hope you and her learn a way of helping her soon x