StopTheWorldIWantToGetOff
In the Brooder
First time chicken keeper, so please bear with me! 
I collected 3 rescue hens 5 days ago - so I am assuming they are around 18 months old.
One of them clearly has a health problem, but I am not sure what it is. She appears to have no feather loss apart from her tail and around her vent – the other 2 rescue hens have an oven ready look about them.
She is eating and drinking and moving around normally. Other 2 keep picking on her and pecking her bottom which makes her squawk.
She hasn’t laid any eggs, other 2 have laid every day since collection.
It took me a couple of days to realise that her vent was very dirty, in my defence it is harder to see as she still has a fair amount of feathers around her bum.
I have been adding ACV to their water from day 1 and today added Avipro Avian probiotics to their feed. Today I gave her bottom a wash and was able to take these photos.
Her poo is a mix between fairly normal and mustard yellow – see pics.
Any advice gratefully received.

I collected 3 rescue hens 5 days ago - so I am assuming they are around 18 months old.
One of them clearly has a health problem, but I am not sure what it is. She appears to have no feather loss apart from her tail and around her vent – the other 2 rescue hens have an oven ready look about them.
She is eating and drinking and moving around normally. Other 2 keep picking on her and pecking her bottom which makes her squawk.
She hasn’t laid any eggs, other 2 have laid every day since collection.
It took me a couple of days to realise that her vent was very dirty, in my defence it is harder to see as she still has a fair amount of feathers around her bum.
I have been adding ACV to their water from day 1 and today added Avipro Avian probiotics to their feed. Today I gave her bottom a wash and was able to take these photos.
Her poo is a mix between fairly normal and mustard yellow – see pics.
Any advice gratefully received.