This she is spitting out bits of chicken: I suspect she isnt weaned. The owner didnt gave them kitten food, thinking they gets milk from momma... And momma probably didnt get much either, but a momma can always scavenge something...
So you will be forced to learn her to eat proper food.
But first, manage the crisis, by forcefeeding etc...
I forgot I mention sometimes kittens need to be stimulated to urinate or defacate...take a soft cloth or cotton and wet it with warm water and gently massage the genitals and rectum until urine and/or feces is produced.