I would suggest reading this thread....
Bird Safe Fresh Foods & Toxic Food Lists + Sprouts
I would not recommend feeding peanuts at all, but do feed a variety of foods... instead of feeding dry seeds, try feeding sprouted seeds! Keep the protein low in the diet, but be sure to feed foods high in vitamin A!!! You could supplement the diet with red palm oil. You may also want to add
Essential Fatty Acids to the diet in small portions.
Some good foods in particular to feed include the following...
Cherries or Black Cherry Juice
Milk Thistle (extract or?)
Flax (freshly ground or oil)
Dandelion Roots/Leaves (fresh, no pesticides/chemical fertilizers)
Aloe (juice or fresh from the plant)
Might want to look into probiotics, full spectrum lighting, and possibly a vitamin supplement.
What tests did the vet do? Did they recommend any particular diet? Can you find out what the 'parrot blend' you are now feeding?
Ideally, you want to be feeding a variety of fresh foods daily... such as mixing cooked grains, cooked legumes, fresh/frozen veggies, and some fresh/frozen fruits together.