Is this HIKUI?

[Rhern]

Hello koiphen group it’s been a while since my last post.
Well I have this beautiful Matsue Kohaku which was doing great.
Early December I saw what appeared to be damage on the side no big deal I figure she banged against some as she is behaving normal.
Fast forward and the damaged yellowing is spreading to the other side and head.

Also about three weeks ago the red is beginning to “come off” on the head
The red coming off started small and seems to be spreading.

I have scoped twice and found nothing.
For NOW it’s the only koi that has it.
Seems to be only on red for NOW

Any ideas?

I have plans to isolate in 750 gallon qt until I know what it is.

So far I did a salt dip yesterday and started feeding medicated food.
Should I salt qt?
Should I start oxolinic acid dips?

[Rhern]

More pics

[Rhern]

?

[coolwon]

What do you feel if you run your finger over the suspected area?

[Rhern]

The sides of the Koi where the scales are feel like scales and the white on the head feels smooth it only looks as if the color is coming off

[coolwon]

Windows and gin rin?