While she’s on corid don’t give her any vitamins until she’s completed treatment.
You can try mixing her feed in water to make a soupy mash, sometimes this can encourage them to eat. Another thing to try if you have any banana is to give her one inch slices, if you dampen them then they slide down the throat fairly easily, she probably won’t like the texture if she’s never had banana before so you’ll have to shove it down her throat.
Not knowing what’s wrong makes treatment difficult but the position you’re in is pretty common for us backyard poultry owners so we do the best we can. Her symptoms are vague, it could be upper or lower respiratory, lower digestive infections can mimic lower respiratory infections, she’s fluffed and her neck being outstretched shows she is seriously sick and something in her abdomen could be hurting.
If it’s a fungal infection or internal bleeding unfortunately that isn’t something that ban be treated at home, both of those require veterinary care.
Otherwise her treatment will depend on trying to cover the more common causes, bacterial and parasite.
The best anti coccidia drugs are corid, Toltrazuril, and SMZTMP. Corid is easier to find than Toltrazuril unless you happen to know anyone with goats or a horse tack store in your area.
SMZTMP is a broad spectrum antibiotic that can knock out a lot of things as well as coccidia. It’s generally safe but should not be given with potassium rich foods, like banana.
Tylan/ Tylosin is another excellent antibiotic that will treat lower digestive disorders like clostridium and salmonella as well as respiratory infections like mycoplasma among others
Amoxicillin is effective against a lot of things but not as strongly against clostridium.
Baytril is a powerful broad spectrum antibiotic that will tackle a lot of things, though mycoplasma isn’t as sensitive to it as Tylosin.
If it’s worms, which is less likely in geese Fenbendazole “safeguard horse wormer” will treat most, it also treats Giardia to an extent. Ivermectin doesn’t really seem that effective on worms anymore.
Metronidazole is the main treatment for clostridium and Giardia.
Birdpal products has amox and corid among other things.
https://birdpalproducts.com/products/amoxicillin-capsules-250-mg?_pos=3&_sid=49addc133&_ss=r
https://birdpalproducts.com/products/corid-solution?_pos=1&_sid=16c7f3243&_ss=r
If she’s starts refusing to eat anything you’re going to have to start tube feeding her.
You’ll need a 60 ml catheter tip syringe and a catheter tube, something like this
https://www.amazon.com/Pieces-Rubbe...&keywords=Catheter+tube&qid=1741132148&sr=8-6
You’ll need poultry start or game bird start, the higher the protein content the better.
Mix a little start with boiling water until you’ve created a smoothy like consistency, you’ll probably have to keep adding water because it expands and gets gummy.
When it’s cooled enough that you can stick your finger in it but still warm fill the whole syringe, try to make sure there aren’t any big air pockets, this can be tricky.
When you’re done squat over her back so she can’t move but don’t sit on her. With one hand apply pressure to the corner of her mouth until she opens, then slide the tube down HER right side of the throat, it will be hard to see the lump sliding down because her feathers are fluffed so you’ll have to feel for it. When the end is near the base of her neck hit the plunger.
The faster you do this the easier it is and it’s less stressful it is on her.