Awww, poor Daisy, and poor you too, you've all been through a lot!
A painful mouth, even if it's resolved now, might have scared her off eating. It sounds like you are doing the best that you can for now. My one trick is to change the feeding vessel. Food that Lila rejected in her bowl was eaten eagerly off a paper plate.
I know how hard food issues can be and the stress and anxiety around feeling like you are spending all of your time trying to feed the dog. Hang in there!