Turquoise rainbow tail has red bumps

[Potluck]

So I was doing my weekly water change today and noticed 2 red bumps one on each side of his tail, exactly the same spot on each side one side looks like it's flaking, not fuzzy or cottony like the skin is flaking like a human would after a sore is healing, he's very active, eating like a pig but he's also very mean to the other rainbows I have left, this is My oldest rainbow (5 years) has never had an issue and even survived when my tank went through the dreaded columanaris, I did introduce rainbows a few months ago I added 6, have 2 of them left, I also added 2 Dwarf neon rainbows but they became snacks for mr grumpy (turquoise), the red irani, 2 emeralds and 1 boseman that died all had what looked like moles/warts and I believe dwarfism as none of them grew, I don't know what this is but I'm worried about tuberculosis /columanaris, I couldn't take a pic cause he's never not moving so I took a video hopefully you can see it well enough, I don't want to lose another rainbow im afraid it will make me quit the hobby.

Ammonia 0
Nitrite 0
Ph 7.5
Nitrate 15
Gh/kh both at 6
Phosphate 1.7
Temp 80

https://youtu.be/iWL2qEeINaQ

 

[Delapool]

Gosh, he moves quick.

Imo, I'd remove to hospital tank and treat for bacterial infection. Is there any other redness around any of the base of fins? I had something similar on base of tail for neons. I can't say it is the same but would shift to a spare bucket or container for sure.

If its viral, then he should come out anyways unfortunately.

 

[V227]

The lesion looks to be symmetrical on both sides. IMO probably a viral cyst. Nice looking tank. Don't quit the hobby. Every aquarian has these unexpected setbacks.

 

[Potluck]

The lesion looks to be symmetrical on both sides. IMO probably a viral cyst. Nice looking tank. Don't quit the hobby. Every aquarian has these unexpected setbacks.

Yeah it's exactly the same spot on both sides, but what do I do about a cyst? He never had anything wrong with him until the other rainbows, every other fish is great, this guy survived columanaris he's a fighter I'd hate to give up on him.

 

[Potluck]

Gosh, he moves quick.

Imo, I'd remove to hospital tank and treat for bacterial infection. Is there any other redness around any of the base of fins? I had something similar on base of tail for neons. I can't say it is the same but would shift to a spare bucket or container for sure.

If its viral, then he should come out anyways unfortunately.

No there no redness anywhere else but those 2 lumps on the base of his tail, he eats like a pig, and mean as a snake as he's the dominant male, I've had him since I first started this hobby so over 5 years now man time flies.

 

[V227]

I've only had to deal with a viral cyst once, on an older Denison Barb. He also was big and active when the cyst developed. It didn't affect his behavior, but was very ugly. The growth surrounded his mouth like a cold sore. After several months the cyst shrank but never completely vanished. The barb aged out within the year. No other fish was affected.
You noted that the Rainbow is older and that he survived a bout with Columnaris. Maybe all that combined weakening his immune system, allowing the virus to take hold.
There are no treatments for viruses. I don't think it's particularly contageous. Im sure you are researching the subject and will make the correct decision.