6 week old chick not doing well

[Summere]

Hello,
I started with 12 day old chicks and they just turned 6 weeks, today the smallest one of the group is slightly lethargic, breathing heavy and her belly feels swollen and hard, checked and no pasty butt, any suggestions ??

 

[Livia Ammon]

I had one like that. She seemed unhappy but I can’t for the life of me tell what was going on.

 

[Eggcessive]

Hello,
I started with 12 day old chicks and they just turned 6 weeks, today the smallest one of the group is slightly lethargic, breathing heavy and her belly feels swollen and hard, checked and no pasty butt, any suggestions ??

What feels swollen and hard—her crop or her lower belly under her vent? Is she pooping and what does it look like? Can you post pictures of her, her belly and poop?