glad she is feeling better!
Dexter has been TERRIFIED of grooming since i got him. shaving in steps can be a really good idea, especially since you said positive reinforcment has been improving her slightly. it has taken me 4 years of positive association with scissors to be able to give Dex a hair cut without him getting so stressed out that he bites. he now is at the point where he comes to me, head down and sad, and just sits veeeeeery still while i snip away for a short while and then give him a treat and a celebration. it takes about 3 days to give him a full groom! when he was at his worst, i would snip away one bit of hair and throw a huge puppy party with treats and leave it for a couple of hours and then do another snip and another celebration. it takes a lot of patience, but it can be done! taking it slow makes the stress not build up to a boiling point.
good luck!