What is the most logical next event?

How to stop a macaw from feather picking or chewing
Get a complete physical examination.
Take your macaw to an avian veterinarian for a complete physical checkup. Get blood tests done and test for hypothyroidism, psittacine beak and feather disease.
Ask the vet to analyze a dropping sample to test for intestinal parasites, like giardia. Although feather picking is often the result of psychological distress, it's important to rule out any underlying health conditions.