For egg binding, you have to put on gloves, lub up and stick your finger in her vent and feel around carefully to see if there's an egg... I'm glad she's hanging in there!!
I would treat with Corid ASAP, like Judy said... TSC carries it.... . Also has she been dewormed? If not and the corid doesn't seem to help I would worm her with Safegaurd .... Have you seen messy or bloody stools? Also check for mites and lice while your at it... They can make a chicken become...