Fluids, oil and massage are required.
Isolate her from anything fibrous... grass, straw, hay etc possibly even shavings and dry or lumpy food. You need to provide clean water, a vitamin supplement like Nutri Drench and extremely sloppy food made by mixing her regular pellets or crumble with a lot of water to make a thin slurry... you can add the vitamin supplement to that or the water or giver her a few drops direct into her beak if she is not eating and drinking of her own accord. Chunks of solid coconut oil (from the fridge) can be the easiest way to get oil into them and I believe you should aim to get a teaspoon of it down them. The start to gently massage the crop contents. If you are doing it right, the bird should be reasonably relaxed and enjoy it. If the bird is not comfortable be ease off and be more gentle. You are aiming to knead the contents to break them up. You may need to encourage her to drink to assist the process.
Aim for 10 -15 mins of massage 3-4 times a day and make sure the only thing she has access to is the water and very sloppy food. There is no point in giving her anything else apart from a few drops of Nutri Drench twice a day, because it will not get beyond the blockage and may just add to it.
It could be that the problem is lower down her digestive tract. Some reproductive ailments cause masses to develop in the abdomen and these can push against the gut and constrict it. There will usually be some pretty obvious abdominal swelling either between the legs or below the vent if this is the case. Cup your hand between her legs to feel for this and compare with a healthy chicken so you know what is normal. They will usually have some soiling of the vent feathers if there is abdominal swelling and poop will sometimes be mostly clear or white urates. If this is the problem then there is less chance of resolving it unfortunately.
Lest us know what you find and we will guide you from there. I massaged a couple of my hens for almost 2 weeks before the impaction broke down so don't worry too much if it takes a while. The important thing is to get fluids massaged through the blockage and not allow her to eat anything that will add to it. Think about it like a kitchen sieve. Anything that is not fine enough to pass through it will just sit there and make it harder for other stuff to get through.
Thing is when a chicken stops eating... they are much worse off than we realize, as prey animals they will try to hide any weakness. When was her last egg laid?
