So sorry Ida Mae is sick.
You could call the Avian department at the U of PA Veterinary School in case they can address faster or more skillfully (if the "exotic" vet advises that they know little about chickens - did they say?). Not sure where in SE PA you are but they are, as you know, in the Philly area. If they can't talk to you about Ida Mae in real time or see you quickly ask them to recommend someone in the area who can - be persistant - it's easy to get the run around in such a big place. Been there, done that, with them but I just didn't stop till I found someone to talk to (I don;t think I have that contact info any longer...).
You might also do an urgent BYC post asking for avian vet recommendations in the SE PA area - put that in your post title "URGENT - need vet rec for southeast PA" .. I know of a few avian vets in north central Jersey (that may or my not be good) but they'd probably be a distance from you - a long distance could be a lot of stress on Ida Mae, I don't know..
If Ida Mae has worms, a better treatment than DE at this point would be Ivomec Eprinex (spot on treatment placed on back of her neck). Can order on line or find at places like "
Tractor Supply" stores. I'm in central Jersey and would be happy to give you some - I may be in Philly Thursday but that's your vet appointment day - so the logistics of us trying to connect may not be that helpful to you..... do bring a very fresh stool sample to the vets with you though - I'm sure you plan to.
She may have become an internal layer since she is only 2 1/2 and not laying at all, in which case she may have infection going on. Sometimes the right antibiotic and maybe anti-inflammatory can beat that back, for awhile anyway.
The "retracted" head/neck doesn't seem to comport with that though so maybe she does have a crop issue. X-rays may reveal her problem.
Drat - I am so sorry - I know what a worry it is to see them feeling unwell and to know they are counting on you to figure it out. I hope very much the help you need will be out there and that Ida Mae will get well. Please keep us posted. If you are able to keep she and her sis together at least part of each day it sounds like they would both be comforted by this.....
JJ