I found this article on chick mortality:
https://www.backyardchickens.com/t/39604/some-causes-of-early-chick-mortality
Halfway down the page it describes this and suggests whole/raw milk, :
"Coccidiosis and Necrotic Enteritis
Coccidiosis and Necrotic Enteritis are often confused, as the symptoms are similar. The symptoms include pasty butts, diarrhea, lifelessness, excess water consumption, and eating shavings. The difference will be blood spots in the manure. Blood spots are a clear indication of Coccidiosis. The good news is that both problems can be treated the same way. MANAGE YOUR LITTER! That was simple. Whenever you see clumped litter (generally around the feeder or waterers) you have harmful bacteria and/or coccidiosis. Actually there are several precautionary steps that can be taken. First, keep the clumped litter removed. Second, raise the feeders and waterers so that the lip of the feeder and waterers are level with the average birds back. Third, periodically apply thin layers of new shavings on top of the old. Fourth, maintain a good AIR FLOW.
Most occurrences of Coccidiosis and Enteritis will occur in the brooder. Generally symptoms will become noticeable around day 10. The mortality will peak between day 14 - day 21. Then the deaths will slowly reduce because the remaining chicks have built their own immunity to coccidiosis. If either of these problems have gotten out of hand and you are in the middle of a crisis, feed whole / raw milk to the chicks for 7 days. This will coat the stomach and soothe the pain so they can continue to eat and drink normally while the immune system kicks in and protects the chick. This is the easiest method."
However you didn't mention anything about diarrhea so I'm not sure if Balthazar is suffering from this. Stay strong little Balthazar!
https://www.backyardchickens.com/t/39604/some-causes-of-early-chick-mortality
Halfway down the page it describes this and suggests whole/raw milk, :
"Coccidiosis and Necrotic Enteritis
Coccidiosis and Necrotic Enteritis are often confused, as the symptoms are similar. The symptoms include pasty butts, diarrhea, lifelessness, excess water consumption, and eating shavings. The difference will be blood spots in the manure. Blood spots are a clear indication of Coccidiosis. The good news is that both problems can be treated the same way. MANAGE YOUR LITTER! That was simple. Whenever you see clumped litter (generally around the feeder or waterers) you have harmful bacteria and/or coccidiosis. Actually there are several precautionary steps that can be taken. First, keep the clumped litter removed. Second, raise the feeders and waterers so that the lip of the feeder and waterers are level with the average birds back. Third, periodically apply thin layers of new shavings on top of the old. Fourth, maintain a good AIR FLOW.
Most occurrences of Coccidiosis and Enteritis will occur in the brooder. Generally symptoms will become noticeable around day 10. The mortality will peak between day 14 - day 21. Then the deaths will slowly reduce because the remaining chicks have built their own immunity to coccidiosis. If either of these problems have gotten out of hand and you are in the middle of a crisis, feed whole / raw milk to the chicks for 7 days. This will coat the stomach and soothe the pain so they can continue to eat and drink normally while the immune system kicks in and protects the chick. This is the easiest method."
However you didn't mention anything about diarrhea so I'm not sure if Balthazar is suffering from this. Stay strong little Balthazar!

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