Chick lethargic, how to diagnose?

[Misskk]

This is my first batch of chicks btw, so very much a newbie.

I have a 3ish week old barred rock chick, she was fine yesterday, today we went out to the coop and she was sitting in the corner with her eyes shut. All she wants to do is sleep. She's not interested in food.

Yesterday they went outside for the first time, other than that nothing in their routine has changed, and the other 9 barred rock chicks seem fine, and are all walking around, flapping and eating.

I moved her to her own box with shavings, water and food, and she was exploring it for awhile, seemed more energetic. She tried to jump out a few times, was flapping around, cheeping, etc. Now she's settled back down to sleeping.

I attached a poop pic. What should I check to diagnose her? Nothing else seems off, her breathing is normal, her eyes look fine, she's not pasted up. That's the extent of what I know to check.

 

[Wezdin]

I would give sav-a-chick or nutri drench if you have it available. How warm is it where you live? at that age they should still have heat.

 

[Misskk]

I would give sav-a-chick or nutri drench if you have it available. How warm is it where you live? at that age they should still have heat.

It's 62 degrees outside, they usually stay in a garage with a heat lamp, yesterday they were in the sun when they went out so I didn't bring out the lamp.

I'll look for nutri drench, thanks for the suggestion.