I think its Pox ?

Hi guys,

Would really love some help here, im worried about my babies.
I had a hen disappear for a month, tuns out she was hatching under the hen house.
She has come out and been fine for a few weeks but has exploded in blister like lesions on her head, not on her feet, I have pout her aside in a coop on her own, out little rooster had white mould looking spots appearing on his head and he is now separate too, I have now noticed on some of my chicks in a separate yard little growths on their feet. I rang the vet and am getting a vaccine tomorrow but how do I treat ones currently infected as it seems that they all have it in one way or another.
They look so uncomfortable.
I think all 20 are poxy.
Any advice?