What is your general location? Do you have vet school with a poultry dept in your state where you could send the video for opinions? Tremors is neurological. It can be seen in some baby chickens up to 2 months old with avian encephalomyeopathy (AE) which is sometimes called epidemic tremors. Most chicks die, but survivors don’t usually have the tremors when they have recovered. Is there anything such as a toxin, weed killer, fertilizer, insecticide that he could get into? Does he get along okay besides having the tremors?