I used to be dog man in my local pet store and SO many people go through this stage. Before I say anything about its probably not an issue, but I have a few questions.
DO you feed him kibble? I know you feed him chicken but is that with kibble or with other foods? and this leads on to A) what brand of kibble or B) what other things?
As he is getting older and more active he might for example like a little more red meat in his system, lets see what you come back with.
AS of now how often a day does he eat? is the bowl out all day or do you have set meal times? Also do you handle his food before you give it to him, or do you try to avoid it by using tools like scoops, knives tongs etc?
What kind of dog is he and what size? How much food do you feed him (per day, per sitting, however you want to quantify it but preferably in weight) and how much exercise does he get? also slightly weird one but revealing, does he smell? (in his coat or his flatulence)
Like i say its really nothing to worry about all dogs go through this stage, some grow out of it others don’t, it could well just be that he will stop growing so much now and doesn’t need so much food and energy. There is a small chance he is missing something in his diet, but from your caring messages I’m sure you have already checked that he does, either way im happy to double check.
It may also be that he is getting enough food and nutrients from what he does eat and has found his own balance. Dogs are good with this, no matter how much we train them at the end of the day they are still dogs and generally act on impulses like hunger, no hunger no food. Two things you can do there, A) reduce his food, B)increase his exercise. If he is losing weight you could try adding a little something to his food.
Im exppecting a proper essay back and Im looking forward to it! more info the better