White runny substance from vent

I have a week old chick that had pasty butt after arrival. When I cleaned the pasty butt a white runny substance started coming from the vent area which also looks protruded. I keep cleaning her up but it doesn't stop. I just noticed that it appears the other chicks with her have it on them. Can anyone tell me what this may be and what I can do for her. She is also wobbly on her feet today. Thanks.