Had a look at the poo pics @BayBay Peepers thank you, very useful. In general their poos are a little watery but normal enough I think and I've just separated her so I can see her poo alone. I'll post a pic when she goes.
The other three seem fine scratching about as normal.
Thought I heard one of my other rescue hens cough a little, they're separated by a wall, would it be too late to move them in case of any disease spreading?