Gapeworm??

[Kateslilfarm]

She is pooping a little bit. It’s fairly normal consistency small poops.

They have at all times chick feed, high protein feed, layer feed, grit and oyster shells. I have a mixed flock of breeds and ages. Oldest is 1.5 years old, youngest is 4.5 months old. So to cover all of their needs there is always a variety of feed out. I also give them fresh greens, and other fruits and veggies. The only thing she will eat at all at this point is scratch grains because it’s her favorite thing. I also offered her a mash of feed with rooster booster and she won’t eat it.
She has no respiratory symptoms or discharge at all.
And no improvement as of yet with giving her fenbendazole. :-(

She is not not moving around much. Her left foot is not extending normally so she can place it on the ground. She is sitting most of the time. I’ve tried feeding her mash as well as pâté cat food. The only thing she will eat is cracked corn or scratch grains. If she she does get up and move her balance is off.
I did lose two other birds to what I now suspect may have been Mareks. None had the classic symptoms, but all 3 of them have some of the symptoms. Also none of them were vaccinated.

 

[Kateslilfarm]

I'm very sorry you're going through this with your hen.
Its my understanding that gapeworm is very uncommon, and i would hypothesize some kind of other internal issues instead. What color is her comb currently? Is it dark? A dark/purple-ish comb along with gasping would tell me that she has some sort of respiratory infection (a dark purple-ish comb might suggest lack of oxygen). What color is the little bit of poop that she has?
I've had a hen with a respiratory infection once with similar symptoms. She was underweight, very weak and gasped a ton. (Also had a dark comb and little appetite). Unfortunately she didn't pull through...
Hoping for the best.

Her comb is pretty red. She had no other respiratory symptoms, no discharge, couching etc. her poop is greenish abs some have the white urea caps.

 

[rascal66]

Her comb is pretty red. She had no other respiratory symptoms, no discharge, couching etc. her poop is greenish abs some have the white urea caps.

If I remember right, sometimes green poop is a sign of infection.. (Editing now because i just saw the poop pics). Actually, her poop does not look like "dealing with infection" poop in my opinion.
Unfortunately I'm also not very knowledgeable on what your next steps should be. Maybe an antibiotic could help, but its hard to know you don't know exactly what's wrong. Hope she can recover.