Well, his diet is not good. GCCs don't do well on pellets or on any free-fed protein food. They are mainly fruit eaters in the wild and need largo portions of produce every day with just low protein (I feed grass seeds) for dinner. No meat whatsoever (there is only one single species of parrots that is classified as omnivorous -meaning they eat some meat, there is another one that is in doubt but neither are GCCs). Brown poop is not really normal poop. Birds poop is always green and it's only brown when you feed pellets and little else - which is not good. There should also be transparent urine in the poop but you mention only brown feces and the white urates but this could be just a mistake on our part.
I don't know where you are physically located so I don't know if the 10 hours of sleep is what it should be happening right now (the hours they sleep varies greatly with the different seasons).
Fungus smell like cheese or yeast and, although it's not a foul odor, it should not be there. And a crop infection, even if it is candida, would not show any white spots inside the beak (you are thinking mammal, not avian) or any change in the feathers on the crop area.
I have no way of knowing if the injection or the crop needle used to aspirate his crop damaged anything but I can tell you that it was painful and terribly stressful for him -as well as useless.
PDD and candidiasis have similar symptoms at the beginning: lack of appetite, vomiting, lethargy, swollen crop. But candidiasis can be treated and usually remains in the crop while PDD affects more organs (even the brain), destroys the crop (it actually disintegrates), it gets worse and kills the bird. You need a diagnosis, my dear, and nobody can give it to you over the internet. You need to take the bird to a vet that knows what to test for, diagnose and treat because you can't take care of this by yourself. For one thing, antifungals are by prescription only (at least, here in the States) but, even if they weren't, you can't just treat for a fungal 'just in case' because, for example, if it was a crop fungal infection, you would also use ACV with the mother but, if it is PDD, that's pretty much the worst thing you can give the bird (imagine how the vinegar would act on a crop that has lesions!).