When a chicken is sick (from any cause- respiratory infection, wounds, cancer) or stressed (from heat, too many environmental changes, improper conditions, etc) they can become lethargic (not moving much) and not eat. Unfortunately, that means not moving and not eating can be due to ANYTHING that makes a chicken feel really sick.
Provide plenty of fresh water, ideally one container of plain, clean water and one with an electrolyte solution mixed in. If you don't have access to poultry electrolytes you can dilute a bottle of Gatorade 1:4 (one part Gatorade to 4 parts water) or add 1 teaspoon salt and 1 teaspoon sugar to about a quart (liter) or water.
Make sure they have shade, and are in a quiet area where they're not bothered by other animals, loud noises, etc.
Yes, feeding them chicken food is ideal, because it has all the nutrients they need, but it sounds like right now feeding them SOMETHING is better than nothing. Keep offering them a variety of foods. If they've never seen produce like greens or fruits, they might not try it right now.
It's possible they had a latent (hidden, and not showing any signs) infection and the stress of moving to a new place has allowed the infection to flourish. If that's the case, hopefully with good supportive care they will get better.
Best of luck to you, and welcome to the forum!
