My favorite pullet- barred rock didnt make it. She had been opening and closing her mouth for days. Not knowing what was wrong i looked up as much as i could. Then i thought back someone at a pet store telling me that I could use foodgrade DE- 'Sprinkle in the pen, on the chickens and could put it on the ground for my pullets to take a dust bath in. I purchased a package of the DE. Doing exactly what she said. I put it down on the ground. All of my pullets walked through it but never rolled in it. I remember my trusting Barred Rock scooping it in her beak like i had given her a great treat. Earlier i had given them meal worms. I felt bad when she dove in the DE like it was a big pile of tasty food. I made sure they had a full thing of fresh water to drink and watched them for awhile. Later that evening my daughter was holding her and she kept opening and closing her beak.I held her. Put her by the water, she drank. The next day same thing. I Checked to see if she had a hard or soft crop area. Her crop was fine but she felt lighter-like she had lost some weight. I put olive leaf in her water and she drank it. I gave her food and she ate it. She still was not right. The one thing I hadn't done was to check her vent. On Monday she appeared to walk slower. I held her and pet her. Yesterday, my husband found her laying in the roost area . What could-should i have done?