That's such sad news. So sorry for you.
Mine seems to have recovered all by herself. She was lethargic and eating little for twelve days. Spending long periods standing still with her eyes closed. Then she suddenly was back to normal. She's not laying still but I'm putting that down to her hormones being all over the place after a period of broodiness. I'd read somewhere that it can take up to five weeks for them to start laying again. She did lay on two consecutive days just days after the broodiness but then stopped again when this lethargy kicked in.
I guess it's hard to know what's wrong. If only animals could talk...