I have a young Delaware rooster (that is in a moveable tractor with other roosters we use for meat birds) that has been healthy so far. Just this afternoon I gave them some scraps, they grab them and run around playing with it. I then heard screaming in the coop portion. I open up the back door and the one roo is rolling all over with his head twisted. I picked him up to stop the flailing but his head kept bobbing. I moved him to an empty smaller tractor and monitored. He was very unsteady on his feet falling to the right, his neck is curved to the right & his right eye won't open. He has a large red skin area at the jaw line at the curve (not sure if it's a mass stretching the skin or no feathers due to the curve his head is making).He is trying to eat the grass (unsuccessful) and drink (seems like he got some water). All of my birds have been vaccinated for Mareks. Any ideas on what it may be ? Will he recover or need to be humanly euthanized?