I have 5 three month old chicks that were hatched by a surrogate broody hen. They had all done so good until a few days ago. I noticed one of the pullets seemed to have a little cough/sneeze, shaking her head, and then occasionally would stretch its neck out and make a loud screech. She also doesn't seem to be eating and drinking as much as the others. I researched and treated for gapeworm but she doesn't seem to be getting better. Today I picked her up and she had a nasty smell that I think was coming from her beak. What do I need to do? Can treating one for worms cause sour crop?