I'm sorry I cannot provide the phone service since I live in the rescue/sanctuary surrounded by multiple macaws who think all phone calls need their input
In any event, with your macaw we know an overgrown beak didn't happen overnight. He has had something wrong for quite a while and once you actually see symptoms, not just the beak, but the lethargy and lack of appetite, chances are it's pretty advanced.
Frequently we find overgrown beaks in birds with what's called hypovitaminosis A, or lack of adequate vit. A in their systems. They get this naturally (never, ever give a vit. A supplement to a bird) in the form of beta carotene which is then converted by the body into the 'just right' amount of vit. A needed and the excess is safely excreted from the body. We see this a lot in birds on a seed based diet, but it can happen to a lesser extent in birds on a healthy, pellet based diet too.
Beta carotene is found in dark colored vegetables like carrots, squash, sweet potatoes, etc..
Another of many, many possible causes of overgrown beak would be disease in the form of internal tumors or cancers (in nature, cancer is nearly unheard of in birds; however, in captive birds we do see it)
There is also the possibility that the bird just doesn't have enough options to scrape and bite and wear down his beak. Chewing objects like wood 'toys' (not toys, but necessities), calcium or manu blocks and the like.
This said, the beak issue may or may not be related to the lethargy you're seeing.
The sleepiness and lack of interest in food are red lights with warning bells going off. Once we see this symptom there is no home treatment, there is no 'watch and wait' protocol, there is simply no other thing to do except get him in to see an avian specific or at least well experienced bird vet just as fast as you can.
It is truly considered an 'urgent care' situation.
Initially the vet should do a blood test and examine a fresh dropping. These labs are not often very costly and if you get your bird in as a 'regular' patient, even the office visit is generally modest. Where I am it's less than $50 for a full, hands on examination and evaluation and probably end up being the very thing that saves his life
To find a quality bird vet call your local Pet Smart or Pet Co and ask who they use. Banfield clinics are usually in Pet Smart's and most of the time have an avian knowledgeable vet on staff; call any and all local vets and ask who they refer to when a client has a bird. You'd be surprised at how many there are just by asking people in the business like this.
Since this little guy should be with you another 25 or more years, it's very worth it to go the extra mile. And once you have a vet established it's worth yearly 'check ups' like with a toddler, just for peace of mind and to keep the vet up to date on your bird's health. This is also an industry 'secret'. The more you remain uppermost in the vet's mind with regular check ups, the more likely you are to get special treatment when your bird needs something, including emergency visits on holidays or after hours.
Please let me know how you make out.