Isa Brown Chick.. Is she sick?

[CiCiClucks]

We recently picked up 10 chicks from a local feed and grain store. We have 2 prairie bluebells, 2 Delaware's, 1 Buff Orpington, 1 Cinnamon Queen, and 4 Isa Browns. All of the chicks are doing great! They are about 3.5 weeks old now and thriving. However! One of our Isa brown chicks is much smaller than the rest. She tends to hide very close to the Cinnamon Queen who is easily the biggest of the bunch. Her feathers are more frazzled than the three other Isa browns and she is about half the size!
She's very calm, but maybe too calm. When handled she quickly sits and her eyes slowly close. This is our first experience with chickens and I don't want to miss something.. could she be sick? If pictures would help I can attach some later! Thank you!

 

[BlessedmamaAELE]

We recently picked up 10 chicks from a local feed and grain store. We have 2 prairie bluebells, 2 Delaware's, 1 Buff Orpington, 1 Cinnamon Queen, and 4 Isa Browns. All of the chicks are doing great! They are about 3.5 weeks old now and thriving. However! One of our Isa brown chicks is much smaller than the rest. She tends to hide very close to the Cinnamon Queen who is easily the biggest of the bunch. Her feathers are more frazzled than the three other Isa browns and she is about half the size!
She's very calm, but maybe too calm. When handled she quickly sits and her eyes slowly close. This is our first experience with chickens and I don't want to miss something.. could she be sick? If pictures would help I can attach some later! Thank you!

Pictures? Sometimes we refer to this as failure to thrive. But it doesn’t mean she won’t grow and end up fine. Sometimes just at a much slower rate. Pictures or video would help.