18 week old pullet sick, clear watery poop, lethargic, day 2. Any advise please!

[surfinghen]

Our 18 week old Domonique pullet is very sick. We noticed yesterday she was puffed up and sitting alone in a corner. We brought her inside offered her some mash with yogurt which she ate a little of, I gave her some water with electrolytes in it with a syringe. She is very weak this morning. I gave her another syringe of fluids this morning, she is still very lethargic.
Her poop is very watery and almost clear with a slight tinge of green.
The other pullets are so far, unaffected.
I live on the coast of norther California and our weather has been hot but not overly hot like 78-80. The coop is in mostly shade.
Of course she is one of the family favorites, any help or advise to what this might be would be greatly appreciated. I've never seen the likes of this illness before so have no idea on how to treat her or what I should be giving her. I am going to the feed store later today if anyone has a suggestion as to what I can be giving her, I can pick it up asap.
Thank you!

 

[surfinghen]

Just an update on our pullet, she passed away this afternoon. If anyone knows what this was I would live to know.
Thank you.

 

[rIrs roost]

Just an update on our pullet, she passed away this afternoon. If anyone knows what this was I would live to know.
Thank you.

Oh no. I'm so sorry she past. I just seen this post. I'm new to chickens so I'm really no help. Maybe someone will be on here that may have an idea what it was. Again i'm so sorry.

 

[Toddrick]

I have read some posts from Kathy, I think, that said when a bird was pooping green it meant food was blocked in their gut, and only bile was passing, and that this was most likely caused by a tumor or organ failure. I suppose it could be caused by a severely impacted crop too.

 

[surfinghen]

Her crop was soft and mostly empty, that was the first thing I checked having had several hens with impacted crops over the years. This was so sudden and not like anything I've seen. I've disinfected the water, and dusted the coop with diatomaceous earth just to be on the safe side.