I'm stumped 2 chickens have died in 5 weeks

[2ndTink]

Their crops are emptying overnight?

Being fluffed up, is keeping warm, but I agree with you, something is a bit "off" with Crazy Eyes. Is there a reason for her name? Do you notice something different about her eyes?
Just asking, I'm not seeing anything about her eyes.

It can be very hard to nail down what's going on sometimes. Re-check crops, look for lice/mites. If you have a vet get a fecal float to see if worms are part of the problem.
If you lose another, then getting a necropsy can often reveal what's going on.

The poop is cecal poop.

Yes, they've been emptying overnight. Crazy Eyes (named because she always seems like she's just wide eye staring, like she's "seen something" been that way since she was little, it's not extreme but she just has this intense and slightly shocked look or something, plus it's a fun name) is left with maybe a tablespoon size crop in the morning ans it's hard / gritty, I saw her all excited about eating grit last week so I am assuming that's what I'm feeling.

My favorite pullet that passed was Spazzy (she would scratch the ground as a chick and immediately fly straight up, she was super odd and entertaining her whole life) her crop was simpleton empty last night when I found her, but the day before I know it had food in it when she went to roost.

I just dosed their water with Corid.

 

[McChooky]

My suggestion is remove the plastic off the vents and leave the heater. The worst thing that we can do to chickens is block the vents and add heat at the same time thanks!

 

[McChooky]

Their roosts are far enough below the vents that they don't get a draft from these vents! If you've got high winds blowing inside your coop from the vents you can make a frame outside and attach it to the side of the coop to block wind but not air(a foot or so from the vents)

 

[2ndTink]

Do they free range? Are the shavings from the same bag as the other coops?
Are they laying?
Are they vaccinated?
I agree with what others have said that a necropsy is in order.

They free range for a few hours in the evening, but not lately, since it's dark early they are roosting by the time we get home, plus we've had 4 snows this month and it's been sticking around on the ground so they've been coop bound more this month than previous ones. December was warm so several birds were molting, a few are still working on getting feathers back and it's pretty darn cold, most days are barely getting over freezing, but we have had some in the mid forties followed by single digits. Yesterday it got up to 36.

I think they were vaccinated for Mareks, but I think that was all. They are laying, I've been getting 3 to 8 eggs a day this winter from the 13 pullets, which now I'm down to 11.

 

[Wyorp Rock]

I've been keeping them inside their coop, 8x10 with a lot of vents

They are in a well ventilated 8x10 coop

Your vents are not blocked off with plastic right?

To get them out more, you may need to shovel out a place for them and put down a little straw for them to walk on.
It's a pain to do, I know. I've had to do it twice this year already, but that's for the group of hens/pullets that roost in trees. Thankfully the snowfall overnight was light and I could take the leaf blower and clear a place this morning for them.

My suggestion is remove the plastic off the vents and leave the heater.

 

[McChooky]

Your vents are not blocked off with plastic right?

To get them out more, you may need to shovel out a place for them and put down a little straw for them to walk on.
It's a pain to do, I know. I've had to do it twice this year already, but that's for the group of hens/pullets that roost in trees. Thankfully the snowfall overnight was light and I could take the leaf blower and clear a place this morning for them.

The vents appear to have clear plastic up over top of them.

 

[Wyorp Rock]

The vents appear to have clear plastic up over top of them.

They do appear that way.
Ventilation is extremely important, even in winter. Maybe even more so in winter...

 

[McChooky]

They free range for a few hours in the evening, but not lately, since it's dark early they are roosting by the time we get home, plus we've had 4 snows this month and it's been sticking around on the ground so they've been coop bound more this month than previous ones. December was warm so several birds were molting, a few are still working on getting feathers back and it's pretty darn cold, most days are barely getting over freezing, but we have had some in the mid forties followed by single digits. Yesterday it got up to 36.

I think they were vaccinated for Mareks, but I think that was all. They are laying, I've been getting 3 to 8 eggs a day this winter from the 13 pullets, which now I'm down to 11.

Chickens closed up in a coop for days or weeks without exercise, sunshine or fresh air will get sick especially if the vents have plastic over them.This heater makes the air warmer and makes the ammonia more toxic thats trapped in there.The OP stated while her husband was in ICU she was working long hrs with little sleep was when the 1st chicken died.

 

[2ndTink]

My suggestion is remove the plastic off the vents and leave the heater. The worst thing that we can do to chickens is block the vents and add heat at the same time thanks!

I haven't added any plastic over the vents, there is a plastic bug mesh and the vent slats. I got a better picture to show them.

Also, yes, same bag of bedding across all the coops.

 

[2ndTink]

Your vents are not blocked off with plastic right?

To get them out more, you may need to shovel out a place for them and put down a little straw for them to walk on.
It's a pain to do, I know. I've had to do it twice this year already, but that's for the group of hens/pullets that roost in trees. Thankfully the snowfall overnight was light and I could take the leaf blower and clear a place this morning for them.

This coop is the best at getting outside as soon as the storms stop. We've been getting snow from the north and the coop is to the north of the run so they always have close to 1/3 of the run clear and a soon as it isn't snowing or blowing too bad they all pop outside. This morning they all piled out, scratched around a bit, a few dust bathed, then went back in like it was too chilly for them.