How is her weight? Is she still gaining or at least maintaining?
I am not familiar with Flubenvet. @casportpony would it be possible to dose her directly into her crop?
This chicken needs nutrition yesterday. If she is eating on her own, that is wonderful. If she isn't, she needs to be tubed.
Not sure if anyone has suggested it yet, but you should be weighing her daily to track weight. That is so very important with sick birds.