Does anyone know what the cause of this is? My quails joint is swollen and seems to have gotten worse, can barely stand up and tips.

[Kiki]

I'd not let him suffer any longer. I'd off him so he doesn't suffer.

 

[Charlie Wooster]

That is a great big enclosure for quail.. I’m surprised you don’t have more injured birds.. they really don’t need that much headroom or open length to run and take off, they have a big burst of momentum when they wanna really take off and fly the sudden stop or impacting another bird wide open will cause injury and death a lot of times..