If you can accomplish this without upsetting her,
Check to make sure she doesn’t have anything visibly stuck in her mouth or throat, gently feel her neck and crop, work your way down and around her body including manipulating her appendages to look for injuries and puncture wounds.
Chickens don’t really like having their combs touched and resist having their mouth examined.
It might be easier to save the mouth for LAST, so
after you’ve examined her body, wrap her snugly in a towel and firmly grasp her wattles together with your thumb and index finger (like a pinching motion) right up under her chin, pull downward while your other hand opens the top of her beak to look inside there.
It might be helpful if someone could hold a flashlight for you.
If you don’t see anything I’d consider setting her up for the night in a dog crate, box or laundry basket with some old clean towels and let her rest.
In case you just unknowingly thwarted a predator attack, Are the rest of your flock secure for the night?