Corrie, I've looked more closely at his photo. The bumpy red area on the wen looks external.. a minor injury that should heal well with clean water, good food, and some time, as it seems to be doing already.
I spotted something else, as well. There are distinct red streaks, enlarged blood veins in the lower fins. There may also be some fin degredation of the tail, but I can't make that out well enough from this photo to be sure it's not just the photo. Those red streaks are a sign of poor water quality.
In this photo, I edited the one you posted to zoom in better on just the fish... to get a closer look.
Here is the red spot on the wen. If this is something than more than just him bumping into something or getting himself snagged, then you'll be able to tell what happens with this going forward now that he's in quarantine. (Paperdragon was right advising you not to add another fish in QT just because he's lonesome. That defeats the purpose of separating one fish from the others if you do that.)
This photo is actually from the reflection (I just flipped it upside down). Looking from underneath the fish, it's redder.
Here is a closer view of the red streaky veins of his lower fins... which is quite pronounced. That does not appear to be normal.
In this photo, I tried to get a better look at Ory's tail finnage. Hard to tell here from the image you provided, so examine that carefully.
In the other thread Lupin linked for us, the tank looks nice. The hut is a problem for them, but you've taken that out already. I thought the sand layer looks excessively deep for the way this tank appears. I would not recommend using that much sand in such a relatively bare tank. The only time I'd go that deep would be when the tank is HEAVILY planted and there's significant bulk to the plants' root system. Without there being a massive amount of plants in here, you don't need more than one inch of sand at the bottom. Reducing the depth of this substrate (gradually, a little at a time while doing regular cleanings)... may help you maintain better water quality.