I think he might have ammonia burns from laying in wet poopy bedding. Is that possible? They must have dry, clean shavings. If you are using a chick waterer stop immediately. They are for chickens and ducks make a big mess with them. Instead, get an old container like from sour cream, and cut holes the size of large spoons in it. Then, fill it with water. It also helps if you put it over a tray covered with hardware cloth. This is my current brooder. I have rubber shelf liner over shavings but not for much longer.