You sure are a very kind chicken mom to your Eddie !!
More challenging: inactive means easy weight gain & more painful to walk, Right?
Feed the nerves that feed the muscles (for animals and humans) !
The B Complex (you do now). Snacks: I learned no more than 1-2 TBSP per day. Sesame Seeds, unsalted of course, for Selenium. Banana for Magnesium & Potassium. But, as she is aged, her digestive system is slowed too. So small portions when eating.
You might try Poly-Vi-Sol, liquid minerals and vitamins (in the baby med section) These are a great source to help a weak hen. 3-5 drops (follow with drops of water to rinse the med taste) once a day for 5 days just to see if it makes a difference.
I have 2 types of arthitis. I'm in alot less pain when I use Trace Mineral Drops, eat small meals and snacks and eat foods that feed the nerves that feed the muscles. Good Luck.
https://opensanctuary.org/article/s...ecial-food-recommendations-for-older-chickens