That's not a good sign:(
For Amoxicillin I'd give it 2X a day.
Seeing thrush or some type of oral/yeast infection is not good, especially coupled with respiratory symptoms.
Is there any odor?
Even though the others are exposed to whatever is going around, you may be able to limit the...
Your package says 5-10 days.
If you had tablets or capsules, I would recommend 10 days, but it's really up to you.
Even with humans, most Doc's prescribe Amoxicillin for up to 14 days depending on what condition is being treated.
Sorry you have sick birds :(
I'd follow Kathy's directions for dosing. For Amoxicillin, I would give for 7-10 days.
Amoxicillin may help with respiratory symptoms, depending on what you're dealing with. If it's Mycoplasma, then the Amoxicillin won't be effective since MG has no cell wall...