You sound like such a sweet soul, appreciating your hens as you do. You might try dex at the end of your cancer girl's life, if it seems she is having difficulty with pain related to inflammation.
Re. gout, I had my mixed flock (four, now two, elders) and four still laying on an all-flock...
These are just hard decisions; you did your best.
It's my experience that chickens actually do express pain, through slumped posture, ruffled feathers, piloerection (sporadic lifting and settling of feathers), immobility and desire (or lack of) to be with flock. At least those are the things I...