Definitely separate her--chickens can be very vicious to their injured fellows! Make sure she is calm, and don't get her all worked up. Definitely get her to a vet!
Without pic it will be impossible I am afraid to give you more specific advice. However it does sound very serious . You are the only one that can see it so you need to decide if it is internal... but for the time being I would do as the others have suggested with the electrolytes (shock) in the water. you must nOT squirt the water in her beak...not only can this distress her more but a bird cannot close off the opening to the lungs as mammals do (there are two holes...one leading to the crop and the other to the lungs) ...
dribble water along her beak if need be to encourage her but do not do it in such a way that she panics. put in in a quiet temp stable place that is CLEAN after cleaning her up. Keep the wound clean. If you can possibly get her to a vet do so.
As we have found with injured chickens (one hen in particular) if flies get to her injuries and lay eggs, you'll have maggots in the wound within a few days. That's really bad. Really important to keep the flies off her injuries!
Those are good signs! Keep her isolated though until the wound is well healed before putting her back with the other chickens.
Any little wound or scab at all and the other chickens may peck at her and un-do the days and weeks of healing in just a matter of minutes and you'll be back where you started.