Poor hen looks up with her mouth wide open, like she cant breathe.

[KCHenlover65]

Is she still doing it?

I just went back there to check on her and she seems to be fine now. I watched them all for a bit. Doesnt seem to be happening now.

 

[Mutchi]

Have any pictures of the hens that would help.

 

[Wyorp Rock]

A video would be good. Upload to youtube and provide a link.

Check her crop first thing in the morning before she's had anything to eat/drink - it should be empty.
Chickens can make some funny looking movements when adjusting their crop, so take time to observe her to see if that's what you are seeing before going into panic mode.

 

[KCHenlover65]

They do adjust their crops and anytime they fill it up so full, I've noticed my own birds adjusting their crops more. If I were you, I'd need to see more signs or get a diagnosis from a vet before I treated for gape worms. Like I mentioned before I am far from an expert so let's get some of our amazing experts to give better feedback

@Wyorp Rock
@azygous
@Eggcessive

 

[azygous]

As @Wyorp Rock suggested, check on her crop in the morning. Gapeworm is not common in this country. It's more likely a crop issue, temporary discomfort if she seems to have settled down. Read through this to familiarize yourself with crop disorders, and check her in the morning to be sure. https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/