Something similar happened when I got a pair of silkies shipped to me. I figured it was from the long flight, I live in AK. The hen was in perfect condition, but the rooster however, was not. He wouldn't walk and if he did he moved backwards. Didn't want to eat or drink and just looked miserable. I called the chicken doctor and he recommend that I tube fed him right away. I did this for about a week, but he did not improve. My guess is that it was from a brain injury. He did have a vaulted skull. He died about a week and half after I got him and I was just devastated. Even though he was sick he was a beautiful bird. I kept in contact with the breeder the whole time and after he passed she worked out a deal with me to get another rooster. The second one arrived in perfect condition just like the first hen.
I hope your little guy improves and the shots work
If we had a vet here that worked on birds I would of taken mine there, but we don't sadly.
I hope your little guy improves and the shots work

If we had a vet here that worked on birds I would of taken mine there, but we don't sadly.