OK, I've been in touch again and passed the info on. Apparently they bought the chickens at a
local market and have already lost half of them with some sort of parasite infection - it sounded like lice from the description. And since the photos above were taken, those blisters have started to burst so it doesn't sound too hopeful for poor Pui-Pui.
Thanks for the advice everyone, and I'll let you all know the outcome. Hopefully she can save some of them and prevent any future chickens developing the same problems.