One of my 1 1/2 week old chicks has diarrhea. She is eating chick starter and gets plenty of grit. She has had pasty butt since she was born, but has had good-formed droppings in the past. What can I do about it? Edit with some more details: The poo comes out with a raspberry sound, and it's khaki green and bubbly. She pretty much just has diarrhea at this point, it's not occasional. Otherwise, she's a happy and active chick.