Another one bites the dust but the rest are thriving

I started to think I was doing something seriously wrong. It had only been one week since the last episode and they were a totally separate hatching group.
Why all of a sudden, my Wheaton maran decided it was time to flutter from the coop at 4 weeks old I still do not know.
I am starting to appreciate that symptoms are very similar for many of the poultry illnesses and unless you visit the local vets surgery for a postmortem you will never know.
An educated guess is the closest you can get and it is quite frankly frustrating.
The Wheaton was four weeks old, and so I expected to be past the most dangerous period, and having mysteriously lost 7 chicks a week earlier I was not expecting further losses.
All the symptoms pointed to cocsiodiccis

Ruffled, spikes feathers
Hunched posture
Shutting of eyes
Unstable on legs
Not eating and drinking very little

The only symptom missing was blood in the droppings.
However the crackle from the chest area when breathing maybe suggested a respiratory infection.

To avoid any further losses I am treating the chicks with Coxoid for 7 days. I will then follow with a tonic to give them a boost.

Fingers crossed and thanks for reading.