How long have you had quail? You may already know a lot of this, but here is what I give new quail owners when I sell them birds.
https://www.backyardchickens.com/articles/coturnix-basic-care.76183/
Are you outside of the US? Those are pretty basic first aid things that every feed store I've been in has. They might have something similar, if not those exact brands.
Can you bring her inside into a "hospital" cage? I use plastic tubs with hardware cloth tops. Make sure she's warm. You might try to entice her with some treats, such as mealworms. If you don't have something like Nutri-drench or Save-a-chick around, you probably want to get some. You can...
Do they have hiding places?
Can you feel her keel?
Does she seem underweight?
I'm concerned that she's not eating and drinking much. That could cause watery poop.
At this point, the best thing to do is to make sure she's warm, and observe. If she's underweight, you might think about...
First thing to do is to separate her from your other birds in case she has something contagious. This will also allow you to observe just how much or little she's eating and drinking, and what her poop looks like.
What kind of quail is she?
Is she eating and drinking?
Does her poop look...