They are a month old?
They should be able to handle temperature lower than 80F. Do you have an outdoor space ready for them?
I'd think about transitioning them outside so they have room to roam and move about.
Where are you brooding the chicks? Do they have adequate ventilation?
A video of the chick so we can see and hear her may be helpful - upload video to youtube and provide a link.
Check the chick's crop to make sure it's emptying overnight.
What do you feed, including treats?