Wild discus whirling and aftermath

Hello everyone, I am dealing with quite a confusing issue. Unfortunately, one of my wild discus recently started doing what is known as ''whirling'' . I immediately took the fish and placed it into quarantine with no medication for a few days, and the whirling has stopped, but the poor thing is looking quite pale. Instead of the gorgeous olive green - blue it appears when happy, it's now a dull brown, with really thick pronounced stress bars, much like the ones they show when breeding. (I'll upload a picture soon, my phone isn't cooperating at the moment). It's become quite reclusive and shy, but if I place any food , it'll be gone if I check in about an hour. I'm not sure what I should do before reintroducing him to the main aquarium, so any help would be much appreciated.

My parameters just in case they prove to be useful:
pH 7 , R/O which is then remineralised
kH 2
gh 5
NH3 NO2 0
NO3 close to 0

I feed them a varied diet of 2 kinds of discus pellets, high protein flake, spirulina and freeze dried blood worms.

Thank you in advance

I'm not sure what may have caused the whirliing but it could be dark and shy now because it's not with the others. If it's eating as good as you say, you may want to place it back in community and keep an eye on it. What's the temp in the tank?

Here are the photos. I too assumed that it could possibly be because he's ''lonely'' though I'm afraid of putting him in an environment where the whirling cause may still be present. Is there any point in keeping him there alone or do you suggest I put him in and hope for the best? I could perhaps do a water change before putting him in (which is supposed to be the cause of whirling ; too many water changes for wild discus is a big no-no) and see what happens. I lost 3 of my 5 discus from my first wild batch and I would absolutely hate to lose another one... The last photo is him in the middle with some of the other guys, the difference is rather obvious I feel...

PS The temperature in the main aquarium and quarantine is around 86 F , but it may get a bit hotter (~87 - 92 due the extreme temperatures we have here during the summer)

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When you say wilds, what species is this and where they adults when you got them, and did you get them from a importer?

Jeanne

How big is the tank its in? If its eating good, maybe you could place one in with it from the main tank and see how it reacts???

It's in a 25gallon bare bottom quarantine tank. I thought I could place one from the main aquarium there, but I wonder if that's just causing unnecessary stress to a perfectly happy fish... Perhaps I should just place him in the main tank and let him be for a week without a water change and see how he does.

It's hard to figure this out when it doesn't do it all the time. I wish I had more to offer.

Keep us updated on your progress...

How long have you had your wilds, are they recently imported ,I don't have much experience with disease, but I'm thinking you have a bacterial disorder of some sort going on, possibly he but don't quote me on that hopefully someone here with more experience can help you out.