agree let the veterinarian know if the changes. Just like with us humans sometimes takes a couple if visits to get everything sorted..
Melaxicam is a pain medication, what was her pain from before?
Diet change , you need to be checking weight. Some birds will not eat enough and starve themselves to death. So you need to check weight to be sure . If her weight was fine and they just want healthier diet then make sure no weight loss. A digital kitchen scale set to grams.
We go by % body mass lost as its difficult to go by weight when we have large sbd small species here.
More 3 % lost check with vet , more than 5% lost get in with vet quickly, 10% or more very sick bird support care snd feeding likely needed.
Calculate by taking grams lost ÷normal weight x 100 = % lost.
Example 5 grams lost normal weight 107
5÷107= 0.046 x 100 = 4.6% body mass lost
Also parrots body temp runs warmer than humans 104plus . So provide extra warmth is supportive and helpful with sick birds. With Temps plunging move burds away from exterior windows. I had to move mine about 4 feet away from windows to get out of that cold pocket.
Seed eater are low in vitamins abd nutrients. A good source would be feeding pepper, bell pepper especially the yellow , orange and red are well liked by most South America parrot species. And are great source of vitamin A! Also try cooked sweet potatoes and cooked butternut squash also tempting many parrots.