If she's regularly spitting up when bending over and has some raspy breathing, I'd begin by treating the crop. Treat as Sour and Impacted.
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/
Feel her abdomen for bloat or fluid, sometimes hens can have the symptom fluid which is called Ascites, this can also cause raspy breathing - a few illnesses/conditions that go along with Ascites is organ failure/dysfunction (liver/heart, etc.), reproductive disorders (cancer, eyp, internal laying) and sometimes it's seen with fatty liver disease too.