You could try a scrambled or chopped up boiled egg. Usually they'll eat eggs. If you have any unsalted sunflower seeds, some of those are good too she'd most likely eat. I've heard others say a little honey in water helps too but I've never done that one.
Since the fecal tests came back normal, and you've done antibiotics, I would recommend giving her some probiotics for two weeks or so, and that could at least help get her flora back and improve her digestive health. It could possibly improve her poops too.
Sugar-free Greek yogurt is one of...