Please help!

Okay so my red rock hen has been getting increasingly worse over that last few weeks. She began feeling very lethargic and having a loss of appetite. At first I was able to get her to drink water and she would eat the grass but now she only grazes and hardly drinks water. She's lost a lot of weight and doesn't have anything in her crop except for a squishy pouch at the base of her chest, lower than where the crop is. I'm really worried. She's been just sitting in one spot for hours now and every once and a while she'll stand up and walk to a different one. It's clear that she's really weak. Her face and comb are red like they should be and she would get occasional hurts of energy. I brought her in today to get some food and water in her and nothing really changed except for neck spasms. They only seem to happen after she eats. She'll swerve it from side to side or it'll fall back. Right now she's sitting down and her neck is in the stargazing position and her eyes her closed and her comb seems to have paled. The spasms are getting worse and she's just laying in this position and panting. I'm really scared and I don't know what to do, please help! I thought maybe it could be a thiamine deficiency but I'm not sure.
This isn't her but this is exactly what she is doing with her neck.

She could have a crop or gizzard impaction. I would do some research on crop impaction here on BYC by doing a search at the top of this page and look for a thread by Two Crows. Gizzard impaction can be more serious and hard to treat. Both of those can be a result of eating long grasses that get stuck in the digestive tract, then rot, causing infection. Sometimes the crop or gizzard can stop working for various reasons, such as a disease, something that has caused damage, or tumors. If you can consult a vet, I would.