Sick hen

[Jule]

I have a hen that has white runny diarrhea and just sits under a chair on porch while breathing somewhat heavy. I lost a hen a few weeks ago acting the same way. What could this be and how do I treat her?

 

[The Coop Crew]

Is it hot there?
When was her last egg?
Has she been wormed?
Picture of the poo would be helpful!