Found one of our chicks laying on its back not able to flip over and walk right

So for context I was out feeding/watering all the animals in while I was doing all that I noticed one of our 8 week old roo chicks was flipped on his back I don't know for how long so I picked him back up and carried him around because they can't breathe super well upside down so I wanted to make sure he was able to breathe while I finished up waters, so brought him inside to show my mom to see what she thinks we tried to get him to walk he wasn't willing to walk until one of the dogs came up and he just kind of fumbled around almost flipping back over, I noticed whenever I was carrying him and he was on the ground he kept on pushing his legs forward instead of underneath of him we ended up putting him down as we'll be gone tmw as we're going to a farm swap and don't have any way to care for him, I've been looking online to see what it possibly could have been it seems like it might have been sudden death syndrome? Has anyone else experienced this? I don't know if this matters, but he was a straight run bantam.