Poor baby girl

Pressure bandages! Sounds odd, and definately fetches some odd looks from passers by when they see a baby in a pram/pushchair with them on. But they really
do help.
My family is cursed with A/E too and my neice really did suffer as a baby and smaller child, they recommended the bandages to not only keep the itching down (something to do with air contact)
and to help prevent her from scratching non stop. Ask your Doc about zinc paste and ichthammol bandages.
As she grows older she will develop a kind of 'ignore' thing and won't be so inclined to keep ripping huge chunks of her skin off.
Oilatum in the bath helps too and you will no doubt have creams such as Betnovate or Eumovate (or similar) and E45 anti itch will help too.
The dairy intolerant bit I can sympathise with too, I am lactose intolerant myself and until you really start to look into every single component of foodstuffs you don't realise just how you can be poisoning yourself

but I'm certain that the docs will have told her Mum what she can and can't eat as she grows up. There are lots more soya based products now to what there used to be. I will have a look and see what I can find on dairy free diets and see if I can find more things to offer her to eat.
Please give darling Ruby a huge big cuddle from me too Batty