I am so sorry your cat has this awful disease. Unfortunately, there is no good treatment and most cats only live for 1-2 months after diagnosis. The main goal with lung-digit syndrome is to treat the pain.
I see that he is already on some pain meds- can you tell me which one? The best pain management approach for something like this is to use 2 or 3 different types of pain medications: a good anti-inflammatory, like Metacam
; an opioid, like Buprenex; and a drug for nerve pain called Gabapentin. Another useful drug is called bisphosphonate which really helps decrease bone pain. You can also inquire about lidocaine cream or gel, to act as a local numbing agent.
One more option is an herbal formula called "Hoxsey-like combination with Boneset". I have had great luck when using this to help animals with bone pain.
Keep up the appetite stimulant. I would encourage her to eat: try cooked chicken or hamburger and rice, canned tuna, Fancy Feast or canned baby food
(turkey or chicken is best).
I hope these suggestions help your cat, and I wish you luck with this difficult diagnosis.