Might she just be heat stressed?
Any other birds acting off, or have loosey poops from drinking more than usual?
Electrolytes might help.
https://www.backyardchickens.com/articles/aarts-extreme-weather-spiel.75893/
Where in this world are you located?
Climate, and time of year, is almost always...
Why do you suspect salmonella?
Is it hot where you live?
This is what I do when I have a bird that is acting 'off':
I isolate bird in a wire cage within the coop for a day or two....so I can closely monitor:
-their intake of food and water,
-crop function(checking at night and in morning before...