Five day old chick going downhill fast

[Wildcatpro]

After incubating and successfully hatching 3 black copper maran chicks I took them to one of the possible mothers who had went broody shortly after we started the incubating to let her adopt them after a few hrs of them hatching and she took to them just fine but today one of the chicks wasn't able to walk and laid there with it's wings out chirping so I put it by the water and it drank and kind of hobbled back to the mom not walking . This evening it still isn't doing good the other two are just fine eating and running around no symptoms and I have given no vaccs of any sort so what do y'all think?? The lil chicks are 5 days old

Isolate the chick
Possible injury
Or maybe sick

 

[nurse_turtle]

Possible injury vs simple failure to thrive. Happens all the time. Sometimes there's nothing to be done. Let Mama hen do her thing.