Sorry that she has not improved. She could try to get her to take some undiluted or concentrated Corid from a dropper. Sometimes we don't know what illness they have until a necropsy after death unfortunately. Worming, probiotics in the diet, or treating a known disease with antibiotics or coccidia treatment is about all you can do. If there is sour crop, here are some links to read:
http://www.the-chicken-chick.com/2012/04/answers-from-chicken-vet-on-impacted.html
http://www.chickenvet.co.uk/health-and-common-diseases/digestive-problems/index.aspx
http://www.tillysnest.com/2012/01/crop-issues.html
http://www.the-chicken-chick.com/2012/04/answers-from-chicken-vet-on-impacted.html
http://www.chickenvet.co.uk/health-and-common-diseases/digestive-problems/index.aspx
http://www.tillysnest.com/2012/01/crop-issues.html