Greetings, I am Dr. Pat. I have worked with birds exclusively for many years.
I am sorry no other expert has taken your question. We all come online at different times, I have just logged in and saw that you have not been answered. I hope I can still be of assistance.
The problem with Greys (I have 2 myself) is to sort through the behavioral vs physical problems. He is trying to get your attention, to help with something making him uncomfortable, but it may be difficult to figure out exactly what that might be.
Several things may help to begin with. Is he getting 12-14 hours dark, quiet uninterrupted sleep at night? Sleep deprivation can be a major driving force with both behavioral and physical problems.
Any changes at home: new pets, children, guests, construction etc? Anything different in his room?
IMPORTANT Check the website for the feed you give, there have been many recalls:
Can you tell me more about the bird?
How long has this been going on?
Where is he from?
Any accidents or trauma?
Interactions with other birds/pets/children/guests?
What is the usual diet?
Has the bird gotten into anything (I know how Greys love to do this)? Chewed electrical wires?
What is your geographic location and local weather?
I would worry about several things: calcium levels, metal toxicity, metabolic issues.
You need to take your bird to see an avian-experienced veterinarian ASAP for complete examination, diagnosis and appropriate treatment. Check
https://aav.site-ym.com/?page=basiccare click on "find a vet"
for members of AAV in your area or call your regular vet and see who they recommend; ask if they really have worked with birds a lot. Unfortunately, this list does not rate competency or experience, but is only a starting place; the vets at least take the avian medicine journal and hopefully see a bird or two a year. The best referrals are word-of-mouth, so check with several non-bird vets, the humane society, parrot rescue groups, bird clubs, etc. for their input. As you might guess there may be controversy and varying opinions even with this. Even board-certified avian specialists may not have a lot of practical bird experience. Unfortunately there are few resources available to refer you to really good, clinically-experienced bird vets.
If this were my patient, and money no object, I would start with complete fecal analysis and direct smear, stained with Sedi-stain and unstained for multiple parasites, fungi, spirals; direct smear stained with Sedi-stain and unstained of the oral cavity; bacterial culture and sensitivity of the feces and choana. Depending on the case I might do a fungal culture. Routine blood work is necessary to rule out other issues such as calcium, metabolic and toxicity. There are MANY DNA/RNA tests for bird diseases. Ultrasound is often more informative than radiographs and does not require anesthesia (ask your vet about this option). Generally I start them out on medications as indicated by the tests.
AAV recommended lab work