Not to worry you, but I did have a maroon bellied conure that died a few years ago that exhibited similar symptoms. Drinking a lot of water and very lethargic. Fluffed feathers and became increasingly disoriented. I noticed the symptoms at around 1 am when I got home from work. Paged the emergency bird vet and by the time they got in at 7 am the bird had passed. After a necropsy, death was determined to be visceral gout. The vet said it was a result of fatty seed based diet and that the kidneys failed which explained the dehydration symptoms. I fed a mixed seed and pelleted diet with fruit and vegetables but the bird typically only ate what it liked, primarily safflower and sunflower seed. The equivalent of bird junk food. I felt horrible because the death could have been prevented if I'd been willing to work with the bird to change bad eating habits (no seed, only pelleted food and fresh veggies).
Hope the vet can give you better news! Good luck with your Quaker.