Can you hear any coughing, chest rattles or wheezes, or see any nasal drainage from him? I would probably give him some oxytetracycline or some Duramycin 10 in his water, in case of a respiratory disease. Tylan is also good. Sulfa antibiotics are sometimes used, such as Sulmet or sulfadimethoxine for coryza, but if he doesn't have swollen pus filled eyes, I would think he might have a virus, MG, or fungal infection. Has it been wet, cold, or any mold in the coop area lately?
Rainy yes. No puss eyes or drainage. Little bit wheezing. Started 2 days ago. Isolated him just to be sure and cleaned coop. No mold or any wetness in there. Seems to be fine other than hoarse and wheezing.
Wheezing and hoarseness could be MG. If he is drinking enough, putting some oxytetracycline in his water would be good. If not, I would give him 1 cc of Tylan 50 for every 5 pounds of weight ORALLY twice a day for 5 days. I doubt if I would give the sulfur, since it might be toxic. At least I know it can really change the pH in the body.
MG is mycoplasma gallisepticum, which some call CRD. It is one of a handful of common respiratory diseases. Symptoms vary from mild to severe with each strain, and can include nasal drainage, watery or bubbly eyes, sneeze or cough, and sometimes swelling of the sinuses causing eye or facial swelling. It is chronic, and can com back whenever a chicken is stressed. Tylan, oxytetracycline, and other antibiotics are sometimes used to treat symptoms.