If you live near a TSC, could you get this?
https://www.tractorsupply.com/tsc/product/durvet-hi-level-vitamin-b-complex
If you get that bottle, draw a few drops out, and carefully give her a drop or two along her bill, leaving time to let her get everything down. You could also mix it in with...
If you could get 400iu soft gel vitamin E capsules, and vitamin B complex pills, or Cattle B complex, that would be better than the poultry vitamin although the poultry vitamin would be good for now. One soft gel a day, and a few drops of the B complex. I would also try offering her warm soupy...