Hen is lethargic, w/ drooping comb, possibly a swollen bottom. What should we do??

[Chickaletta_the_chicken]

We first noticed something was off when her and another chicken stayed inside the coop for awhile. She began standing in a corner and visibly looks ill. Her bottom looks pretty big, im not sure if its swollen? [See picture below]. It seems like its tight, and
I think she may have pooped, shes standing over some (although i didnt actually see her go).
Its very possible that she had been the chicken we were caring for over a prolapse recently, although its since gone in on its own.
Im not sure if she has an egg stuck because im not really sure how to check (im worried if i try, I'd hurt her more, break possible egg..)
Our dog also came and started smelling her, and she didnt attempt to move away.
She took grass from my hand when offered.
Let me know if you need any other information.
Thank you,
Julia

 

[nuthatched]

Hmm.
How old is she?
Diet?

 

[Chickaletta_the_chicken]

Hmm.
How old is she?
Diet?

We have 8 adults in total, 7 would be around 2 years old, and 1 would be older (so most likely 2 but its possible shes the older one)
Theyre fed with crumbles, pellets, a mixture of egg shells and dry corn and are able to go out and eat grass and bugs
They also have recently gotten fed with rice, sometimes with oatmeal or bread

 

[Chickaletta_the_chicken]

Another picture of her bottom:
Shes pretty heavy

 

[nuthatched]

We have 8 adults in total, 7 would be around 2 years old, and 1 would be older (so most likely 2 but its possible shes the older one)
Theyre fed with crumbles, pellets, a mixture of egg shells and dry corn and are able to go out and eat grass and bugs
They also have recently gotten fed with rice, sometimes with oatmeal or bread

She appears to be a sexlink, is she?
Has she laid recently?
How often and how much does she get corn, bread, rice etc?

 

[Chickaletta_the_chicken]

She appears to be a sexlink, is she?
Has she laid recently?
How often and how much does she get corn, bread, rice etc?

Im honestly not sure what breed she is, we got her from tractor supply if that helps. Not all of our chickens lay, but its hard to tell which ones do or dont, would it help to seperate her?
The corn and shells are in a blended feed that they'll get occasionally (it switches out with the crumbles), as for rice and oatmeal, if a big batch is made they may get it everyday while its there.

 

[Chickaletta_the_chicken]

Update: she 'ran' to go to the others who were eating some cooked potato, but shes now back to standing on her own.
Im not sure if we should be trying to feed her anything?
I felt her abdomen and it feels like maybe its full of liquid with something there (but it doesnt feel egg-like?)

 

[nuthatched]

Update: she 'ran' to go to the others who were eating some cooked potato, but shes now back to standing on her own.
Im not sure if we should be trying to feed her anything?
I felt her abdomen and it feels like maybe its full of liquid with something there (but it doesnt feel egg-like?)

Stop feeding them straight carbs. Oatmeal, rice, potatoes, corn, scratch, bread etc are mostly carbs, they're treats for once a week, in minor amounts. They shouldn't be a part of every day diet.
They need a chicken feed, a pellet or crumble to make up 90% of their diet.
The missing feathers indicate that she's being plucked, a sign that the birds are starving for nutrition. (Or cramped/bored)
I think you're girl is a high production sex link, unfortunately, they're prone to reproductive issues and a diet high in junk food complicates what she's already prone to.
Sometimes you can try antibiotics, but usually by the time you see symptoms, it may be too late.