Hello there and welcome to BYC!
Sorry about your hen. Sounds like some sort of crop issue. Either it is impacted or slow or even soured. Crops are best checked first thing in the morning as this is when they should be completely empty. They can feel really funky during the day as the bird eats.
All this being said, if the crop is very hard, it is impacted. If it is soft and squishy, it is slow and perhaps soured. An impaction can come from eating long grasses or very stiff vegetation that the bird can not pass down through the intestines. Many times the gizzard is also impacted as well.
If the crop is soft and squishy, it is slow or soured. Either of these can be as simple as food not moving fast enough, possibly being egg bound or some other life threatening issue.
If she is impacted you will want to separate her or cage her with no food for 24 full hours. Water only. If you know how to get water into her without aspirating her, the crop will move faster. You also use dulcolax gel's squeezed into some water and put down the throat. These will help to break up impactions. Massage the crop often too to help break up the impaction. Inn 24 hours, the crop should have moved most or all of this hard ball and she can go back to eating if this is the case.
For a soft crop, you will want to vomit up the gunk in the crop. This stuff is rotting food and can poison her. Hold her like a foot ball in one arm, beak forward, and support her at the crop with the other hand. Lean forward with her til her beak is straight down, tail up. The MOMENT the liquid starts to come up, count to 2 or 3 and then stand up so she can breathe. Any longer and she can aspirate, or breath it in. Give her a moment to catch her breath, and do it again. Get as much out as you can. You won't get it all out, but she will feel tons better afterwards. Chickens are unable to throw up. So you have to do it for them. Then you will want to separate her so she can only eat her chicken feed. Dampen it so it is more easy to digest. No other foods, at least nothing hard. She can have hard boiled eggs with yogurt on them. Put some probiotics in her water. One human capsule dumped into a quart waterer, dispose of the cap. Change this water daily and make new. Check her crop each morning and vomit if needed. (feel the outside of her breast to see how much is in there. You can use a healthy bird for comparison.) Keep this program up for several days until she can awaken in the morning with nothing in her crop.
You can also post this issue in our emergency section for more help...
https://www.backyardchickens.com/f/10/emergencies-diseases-injuries-and-cures
Good luck and I hope you can get her back to good health soon.
