What is this weak baby chick illness?

[ttrjpbcz]

This is the second time I have come across this. They get super weak....legs have no control etc. They look to be completely delirious.
I can't be the first person to see this in young chicks. What am I doing wrong?
Most recovered with antibiotics, poli vi sol and sunshine, but we lost the 2 tiniest ones.

I would love to know what this is.

 

[lilchick]

Could be Mereks disease. Sometimes they recover.
Sorry about your losses.
Sounds like you are doing everything you can to save them.... good luck.