@Emilysclukscluks, so sorry your hen isn't feeling well.
Can you weigh her?
If she were mine I would start by making sure she is warm enough, then I would tube fluids at 14 ml per pound, wait 60-90 minutes and repeat, and I might even do it once more in 2-4 hours. Even though she is drinking, she is almost certainly a little dehydrated, and hydration should always be corrected before giving food.
How To Crop Feed Your Bird Diagram
This is probably the best tubing video on the web:
https://drive.google.com/file/d/1vUjFZRDp1W3eT9RWJVJ5DBKsFC9cMuYh/view?usp=sharing
These are using a crop needle, not a plastic tube.
This one uses a tube like I use