Sad lessons in chickenhood :( quarantine and culling

We recently adopted 3 new 6 week old chickens from what we thought was a reputable breeder from the many reviews on facebook and yelp. Unfortunately, this was not the case. When we got them home they were infested with lice and then two of the three came down with runny nose, one had heavy breathing, and one seemed lethargic. Their overall health did not look good so I made the decision to cull them to help reduce the risk to the rest of my girls. It was too difficult to maintain good biosecurity with kids.

They were quarantined in my garage in large brooder since we got them on Saturday but I'm terrified that we may have transmitted whatever pathogen it was to my other girls, despite my quarantine measures. After culling, I disposed of all the bedding and bleached everything, the floors of the garage and the walkways. I bleached all the walkways to the coup as well.

Is there anything else I should do?
I do have a feed bag that was stored in the garage as well, it is not opened. Would you even use it?
Is there anything I can do to boost the health of my other chickens? I was thinking of adding electrolytes to their water and a little warmth in their coop, especially since it is supposed to be 9 degrees soon and there are only three of them in a mid sized coop.
What should I have on hand if my other girls come down with something?

I feel so stupid that we got these chickens, I should have gone with my gut

Now we're just wait and see with the other girls.

Sadly you you have carried the respiratory disease to the other birds...On your shoes......
It is highly contagious.....An antibiotic in the water once the birds show symptoms....Hopefully your Birds will be fine......

The feed in the garage is your call?

I brought home to my flock ILT Virus in new Chicks I bought.....I manage the virus....I heat my coop and keep thing stress free.....

One cough from a sick bird is all it takes......



Cheers!