Is he drinking or eating today? I would hold a small cup of water to his beak often, and also some watery mushy chicken feed. Cooked is good as well. If you should lose him, and I hope not, you can send or take his body (keep refrigerated but not frozen) in to your state vet for a necropsy to get a diagnosis. Here is a link where to do that and contact info:
http://www.metzerfarms.com/PoultryLabs.cfm
http://www.metzerfarms.com/PoultryLabs.cfm