A few things you can do to perhaps help your birds. I would lower the temperature in the brooder and look at how you are actually measuring the temperature. Make sure your thermometer is at chick level, not on the floor. Also watch the chicks to see if they are huddled or staying away from the light. This is the best indicator of chick comfort I think.
Make sure your birds have lots of water. If they only have one waterer, put in a second.
Make sure you are feeding a starter with amprolium to prevent and treat any cocci.
Also make sure the box you have them in is large enough and clean. High levels of ammonia can cause respiratory distress as well.