Maui's aging :(

Maui hasn't been doing well lately. Last month, she began to really slow down. I noticed that she was climbing around her cage quite slowly. A few days later, she could hardly stand up and by the end of the day, she couldn't stand. It was terrifying to see her on her perch, with her wings resting on the perch and her head dangling down as she was unable to hold it up. Surprisingly, Maui maintained her weight. I just had to hand feed her and bring her water every two hours or so. She stayed really chirpy and making noise until this day as well. I rushed her off to a nearby avian veterinarian. They took a blood sample and x-rays and ran all kinds of tests. In general, the outlook is pretty gloomy. She doesn't have anything that really stood out to cause her sudden downturn. Instead, everything just looked bad. She has arthritis in both her knees and hips, which is probably making it difficult to stand. She has chronic lung issues, which has weakened her lungs over the years. Her heart, spleen and kidneys are enlarged. Nothing showed up wrong with the blood tests. The vet said she is on the thin side. I have been weighing her religiously for years now. I have noticed that she's dropped about 30 grams, but that was over the course of the last 1.5 years. I try giving her extra treats, but nothing seems to get her weight up. Instead, I figure this is just a new normal for her. The vet sent me home with pain medication and vitamins for her. I thought she wasn't going to make it, but within another couple days, Maui perked back up. She's back to standing and climbing around her cage, albeit slowly. She still has days where I see her slumped over more so than normal, but nothing as bad as that first day. The vet wanted to take biopsies of her lungs and so on, but I called it quits with that. Maui really struggled at the vets. She's way more sensitive than she used to be and she screamed almost the entire time there. Then when I got home, she napped the entire rest of the day. Also, if she is in bad shape, I think biopsies are too intrusive and more than she'd be able to handle. After talking with the vet about this, she did agree. I want Maui to be happy and healthy, but I don't want her on a whole bunch of medication that may not even be helping her. For now, Maui is doing okay again, but she has her good days and her bad days.