When was her last egg?
Check her crop first thing in the morning before she's had anything to eat/drink. If the crop is not empty, then begin addressing that symptom.
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/
Is she should have laid an egg and hasn't, then I'd begin giving extra Calcium asap. Give 1 Calcium Citrate+D3 tablet now, then once daily for 5 days.
Work on keeping her hydrated and for now, I'd focus on her eating the layer feed. Cut out the seed and extra scraps. Make sure she does have crushed granite (Grit) available free choice.
Do you think we could hear the noises she makes when drinking if you videoed it? If so, try to get a video, upload to youtube and provide us a link or you can upload to the
BYC Gallery.
Example of what you are looking for:
View attachment 4001194