One: deep breath
Two: without wishing to sound mean, fences must do what they're supposed to. Emus can scale surprisingly high fences. We're always talking about it here.
Three: 'walking the fence' is a known unhappiness thing. Ok.
Not eating? Sounds also like an unhappiness thing.
Always on alert? Can't be good for her health.
But stumbling and falling? Let's see if any folks in the U.S. have insights on this. Could she be suffering from something else?
Four: My Usual Rant is this:
if, like me, you are familiar with wild emus, you understand that running away is The Primary Tactic. The birds out the side of my house have at this second the option of running fifty miles in a straight line before reaching a fence.
That is, 5k, all the usual unending emu squabbles + massive amounts of space means not too many tears.
(Felicity outsmarted herself once long ago by letting the Legendary Eric cut her off from the gate in the old backyard. In three milliseconds he thrashed a pillow-ful of feathers off her, and knocked her over the fence to boot.)
My point here is that situations in which (a) one emu has a beef with another emu, and (b) that other emu has nowhere to go, just can't be solved in the usual way -- running.
So: fix the fence this minute.
Maybe check Girl Bird for other injuries or sickness. Maybe try to feed Girl Bird some treats.
Watch and wait. Report to us. We are eager to help.
Good luck.
Supreme Emu, Lake Muir, Western Australia
PS A 'sight screen'? We've talked about growing shrubs and small trees in enclosures because the opportunity for one emu to not be in line of sight relieves tension.
Wild birds use this tactic, even sometimes when they know I'm observing them: they'll 'drift' behind a tree or something else.
At this point, even a couple of star pickets extended with some broom handle, and a double bed sheet between -- on the far side of Girl Bird's pen -- might give her somewhere to hand out out of sight. Bales of hay?