I have a polish with crop problems, I picked her up and held her at a downward angle with her head facing the ground and massaged a bit, could hear liquidy sounds and feel hard mass, pushed up starting st her breastbone and nasty fluid came out of her mouth. Did it several times until nothing else would come out. I went to Ace Hardware and got a very small plastic tube about 8 inches long. Put it on the end of a bakers syringe, you can find it in the grocery store with the spatulas and can openers and such. Filled it with mineral oil. Hold the chicken in a towel so it's easier to keep her calm and in place. Wrap your arm around her and open her beak with our hand. Stick the tube down her throat about 6 inches or so, you have to go that far to get to her crop, if not it could get into other holes that will cause her to aspirate, push the syringe to expel the oil into the crop, a couple tablespoons. Pull out tube. Hold onto to hen and massage more. Take a break and repeat in a few hours.
I have done this with 2 hens so far and no ill effects, it makes them feel better, but I am still dealing with the impaction mass. But, the impaction has not had the same effects on mine as yours. They are still up and around scratching etc,..but maybe yours has been like this longer than you knew and therefore hasn't been getting nourishment. That's why the vitamins are so important. You may be dealing with a compounded problem. I would try get her strength back with the vitamins for 2 days before attempting above suggestion, if she doesn't show improvement from vitamins, then do the massage and oil because the final option is probably if she's not getting any nutrition, she will slowly starve to death.