Good news. If the Brewer's Yeast is working you will really start to see dramatic improvements in another couple of days. I am sure it will work and if nothing else eliminate some of her symptoms so you can just concentrate on what is still going on.
Oh, if her stool is still loose and runny you may want to watch for dehydration. When I get an animal with the runs, we call is scours for my goats, I use a Pedialyte mixture (about half pedialyte half water) instead of plain water.
I know with other livestock, their are certain things you can use to firm up the poo, but didn't know what to use for geese. So, I did some digging and found the following article taken from Majestic Waterfowl's website (found here: http://www.majesticwaterfowl.org/mmissue77.htm ) ...hope it helps.
If your duck or goose is experiencing diarrhea it can be indicative of a many number of things. A look at all of your pet’s overall health and symptoms will be necessary in order to determine the correct course of action. Once your vet determines the root cause of the symptoms, a proper treatment regimen can begin.
Diarrhea is often the body’s way of removing toxins from the system, so depending on its severity, your vet may or may not want to interfere with this function—especially in the short term. They may want to lessen the symptom more than alleviate it, depending on the cause.
Adding apple pectin to your pet’s diet is a safe and often effective way to help tighten up your duck or goose’s poop, and there are a few alternatives to accomplishing this.
1) Syringe feed 1-2 tablespoons of organic apple baby food to your duck or goose each day until symptoms improve.
2) Add organic apple cider vinegar to their water (15 mls per gallon)but it can ferment, so change their water frequently! It may also soothe irritated intestinal lining.
3) Kaolin Pectin Suspension (found at farm supply stores) can be administered 2-4 times a day, in doses of 1ml for each pound your bird weighs PROVIDED that your duck or goose is drinking normally.
4) Apple Pectin tablets (250 mgs) can be given to your goose once daily or every 12 hours in more serious cases. Ducks can be given 100 mgs once daily or every 12 hours in more serious cases.
As with all medications, consult with your vet before beginning any of these treatments. Side effects for each of these products include constipation, so only use them under the direct guidance of your veterinarian. Kaolin Pectin Suspension may cause stomach cramping. If you see a decline in your pet’s appetite, discontinue immediately and consult your vet.
Remember, diarrhea can lead to dehydration. Monitor your bird’s drinking habits carefully to ensure normal behavior. If your pet is spending too much time (or all of their time) at the water bucket, bring them to your vet immediately.