What type of enclosure is he in and what are your husbandry numbers like? What type of substrate is he living on? I also agree with frosty on the culture and or tracheal swab to identify the bacteria, fungus or viral cause of the respiratory problem. In the meantime I would take him out of the enclosure to thoroughly cleanse and disinfect it. Place him on paper towels and increase his ambient temperature a few degrees. Keep the humidity at a slightly lower percentage. Maybe at a high 40 percent? Keep us posted.