Well, she is a chicken and maybe her problem was the white thing she ate, which after looking again and reading your description, I am thinking it is some kind of seed. It may have been caught inside her and had to work its way out, causing her not to feel good or eat. Now that it is out, she may be just fine. You stated she is drinking, so give her some food also. I think as long as she eats and drinks she will pull through.