Wow, Stephanie, you have a really challenging situation here. If baby is
fighting any feeding while being held in a normal feeding position, it
sounds like this is somehow painful or uncomfortable for her. During the
medical work-up did they do X-rays? I knew a baby who was a bit older than
this who wouldn't nurse and it turned out to be a broken collarbone - not
that hard to break on a tiny baby...

Until you can figure it out, I'd encourage the mother to feed when baby is
sleeping, to hang over the baby, to feed the baby sitting in a car seat and
any other position where baby seems okay, and to keep supplementing with the
syringe. And I'd want to try to look further for medical causes.

Teresa Pitman