I'm sorry for your loss
Did you take photos of the other organs, intestines, etc.?
You mention she had a painful abdomen - how did she indicate that? Any fluid in the abdomen when you performed opened her up? Any blockage in the intestines?
As for the other one that is not well can you post some photos of her and her poop?
Any pus or discharge in the closed eye? The head twitchy...have you checked her ears for infection, mites, etc.?
Check her crop to see if it's emptying overnight, look inside the beak for any lesions or canker.
Sorry for your loss. Do your chickens have access to grit? I was expecting to see some grit in the gizzard to help break down the food. I am no expert, but I have been told the chickens can get backed up if they don't have access to grit. If they free range, they probably don't need extra grit. But I always have a small bowl of grit in my coop and they do eat it.
I had some grit thrown in a sandbox I had in the run for dust bathing, but I was told recently not to give access to sand so I just removed that and threw grit on the ground in the run yesterday. They do free range when I’m home so majority of the time they have access to everything outside too.
Sounds like it is not a problem with lack of grit.
Why were you advised not to give them access to sand? I use sand in the dust bath for my chickens and they are doing fine. If they eat any sand, it is so small it would just go through them in no time. Don't understand the rationale for keeping them away from sand.
I’ve been emailing with a poultry vet from Michigan State, and he said that he’s seen issues with impaction when feeding chickens on sand. Granted I wasn’t putting their feed in the sand, but I took it away to be on the safe side.
I think the sand (eating it) can be a problem with baby chicks, but I have used sand in my run. Others on here frequently use it in their coops as well in southern climates with a lot of rain.