Have you tried changing her diet, in addition to the massages?
I spent a fortune at the vet's on an impacted crop on my crevecoeur, Blackie, last spring. At the time, she was an indoor chicken, and I didn't realize she wasn't getting enough grit or something (and had overeaten when left under my bird feeder unsupervised). Poor girl! She didn't eat for days, and oop was almost non-existent. I thought she was dying, and didn't know what was wrong with her. Multiple meds, the vet him sticking a long tube down into her to start breaking up the impaction, filling her with mineral oil, all sorts of ickiness.
I massaged, I fed her olive oil and Ensure (yes, the human drink) and her meds in syringes for weeks. It was sheer hell. But he never mentioned surgery. Seems like it took a few weeks to go back to normal.
Then we went away for a week this summer, and when I got back, I noticed her crop was starting to look big again, and she wasn't getting around too well. My pet sitter didn't notice anything wrong. By now, she was an outdoor chickens again, so I suspect it was because he was feeding them all sorts of dry bread as a treat and none of the lovely greens and veggies they're used to. I got to work immediately, dosing her with some olive oil, massaging her, switching her from layer pellets to crumbles, and feeding all the birds large servings of moisture-laden greens and fruit, but cut up into teeny bites, lots of yogurt, and AVC in the water. Anything that would make her start moving stuff through! She cleared up in a couple of days. I never separated her - it would have been too traumatic for her, and she'd worked too hard to get herself back in the pecking order. It's not as though it's contagious, right?