So you are a medical professional? Then step one should be ???? ISOLATE sick birds. Get them away from the healthy ones on the off chance you have something contagious.
It might be the brooder temp. Are the others noisy? Complaining? If there is too much heat it should be obvious because they will pile up away from the heat source. Too cold and they will pile up under the lamp. In either case healthy chicks tend to beech a lot about conditions. Make sure they have good air movement as this is healthy. Provide a range of conditions from very warm to cool and let them regulate themselves. Use a larger brooder if possible. A lot of people, myself included, have used a variety of containers for brooders. They just are not as good as the commercial models. For my money a brooder house is the best way to raise broilers. Canopy type brooder with lots of open space around it. You will find some chicks sleeping against the wall while others are right under the element. Start experimenting but move the sick ones first.
It might be the brooder temp. Are the others noisy? Complaining? If there is too much heat it should be obvious because they will pile up away from the heat source. Too cold and they will pile up under the lamp. In either case healthy chicks tend to beech a lot about conditions. Make sure they have good air movement as this is healthy. Provide a range of conditions from very warm to cool and let them regulate themselves. Use a larger brooder if possible. A lot of people, myself included, have used a variety of containers for brooders. They just are not as good as the commercial models. For my money a brooder house is the best way to raise broilers. Canopy type brooder with lots of open space around it. You will find some chicks sleeping against the wall while others are right under the element. Start experimenting but move the sick ones first.