She could be a runt (in which case she may just catch up on her own) or a failure to thrive case (where they usually don't make it, as there's something wrong internally). I'd just keep an eye on her, make sure she's eating and drinking, and don't go overboard with extras... the chick feed really should have all the nutrition she needs. At most I'd continue with Nutri-Drench in their water for maybe 5-7 days and hope that keeps her peppy.
You can try wetting some feed with water and serving it in a small dish to encourage her to eat. A lot of birds enjoy it as if it were a special treat.
You can try wetting some feed with water and serving it in a small dish to encourage her to eat. A lot of birds enjoy it as if it were a special treat.