I have three week old chicks- Hamburg, leghorn, and Cochin. They arrived very spunky and active. Two nights ago I noticed the Hamburg sounding a bit crackly when sleeping on my shoulder, but she was not panting or showing other signs of stress. Very active, talkative, zoomy. Tonight the crackling continues, and the chick is under the heat lamp panting. I have them in a small stock tank which should have plenty of room to move away from the heat lamp if they’re too hot. It’s a 175W bulb about 1.5ft above the tank. Today I noticed all three chicks spent nearly the entire afternoon napping. The first 5 days of having them they were very active and took brief naps, but not for hours at a time. It’s been a very long time since I’ve had chicks, am I doing something wrong?? They were on pine but tonight I switched them to a bed sheet thinking perhaps the bedding was causing issues. No discharge from any eyes, beaks, or nares. Clean food and water, water contains electrolytes. I only handle them after washing my hands first.