Can you get some Poultry Cell or NutriDrench and give him a few drops daily (maximum 3 ml daily?) He may have some underlying illness that is making him so ill. I would look him over for mites or lice, especially under his vent area and elsewhere. Crop problems can come back and may be a sign of another problem. Intestinal infections, such as coccidiosis or enteritis, or something else might be possible. If you have a local vet who will see him, that might be best. They can check his droppings for enteritis and coccidiosis. Offer wet chicken feed changed daily, and some cooked egg or tuna for treats, whatever he likes to try and get him feeling better.
