Can't figure out what's happening

[Meeshee]

Looking for any ideas on what might be going on. We brought 4 new pullets into our flock. 2 cream legbar and 2 EE's. The EE's are older by a few weeks. I have now lost both legbar. Both seemed to have the same symptoms. Also a few from my older flock seem a bit off. There was red in the pullets poo and we treated for coccidiosis. I didn't treat the older girls as they aren't integrated yet.
Then one of the legbar started deteriorating quickly. Very lethargic, weak and we culled to end her suffering. Now, about 2 -3 weeks later, her sister started being lethargic and weak, white discharge at the end. She passed away on her own today. Was breathing heavily before hand.
As for my older hens, they have started having some red in their poo, occasional white watery poo. All seem to have stopped laying eggs but I don't know if that's the cold or sickness.
They all have come in contact with the same ground. I keep everything very clean and try to spoil them. I'm so sad and trying to figure out what is happening.
I've been giving vitamin water and probiotic water.
Please, if you have any info...
I have bought some antibiotics in case but they have not arrived before I lost my baby today.
I worry about the EE's because they've been housed with the ones that passed away.
Should I treat again? I'm so confused.

 

[nuthatched]

I'm sorry to hear that. Where did you get the new pullets and how long were they quarantined?
What is their diet and approximate ages?

 

[EggSighted4Life]

Should I treat again? I'm so confused.

Welcome to BYC!

Sorry for your losses and experience.

Do you still have the body from today? Sending it in to your state poultry vet/lab for necropsy (if you're in the US, free or affordable to backyard keepers depending on which state) might be a good way to find answers. Contact info for most in the following link..

https://www.metzerfarms.com/poultry-labs.html

 

[Meeshee]

I'm sorry to hear that. Where did you get the new pullets and how long were they quarantined?
What is their diet and approximate ages?

They were about 8-10 weeks (the ones who passed) The other 2 were about 12 weeks when I got them. I've had them for about 6 weeks.
I had the pullets in my yard, in a cage when I brought them home. I'm guessing they probably picked up something on the ground here and I'm so sad about that. I've been feeding the medicated starter chick feed ever since I thought it was coccidiosis. I bought from a breeder and I was told she had "clean chicks". One of the EE's was a big sick after being here for a couple days. She had a nasal issue and a swollen closed up eye. After treating with corid and vet rx she cleared up.

 

[nuthatched]

They were about 8-10 weeks (the ones who passed) The other 2 were about 12 weeks when I got them. I've had them for about 6 weeks.
I had the pullets in my yard, in a cage when I brought them home. I'm guessing they probably picked up something on the ground here and I'm so sad about that. I've been feeding the medicated starter chick feed ever since I thought it was coccidiosis. I bought from a breeder and I was told she had "clean chicks". One of the EE's was a big sick after being here for a couple days. She had a nasal issue and a swollen closed up eye. After treating with corid and vet rx she cleared up.

It sounds more like the new birds brought in a disease, the symptoms are like those of respiratory illnesses. Who knows what was wrong with them unless you have a necropsy done.