I am so sorry to hear about your loss,
You did say he was in quarantine but had recovered, I have an albino too
What I know about Ich, and 'please scientists out there correct me if I am wrong' , is that once a fish has had it and recovered they tend to build up an immunity, like having the chicken pox for us human's and this is one reason why fry and juveniles are more prone.
For example, I don't know what it is
but I have a case of Ich as well, however out of all the fish only the babies and juvenile Bn's as well as the young clown plecos are showing the common spots, have done exactly what you are doing upt the temp. water changes galore, but I don't know how your fishes are acting, but mine although spotty!!!- the babies and juveniles are acting as if nothing is happening, they are eating normally, growing a lot, no sunken eyes, no lethargy, no symptoms of stress or illness in fact, other than the spots they are very dark, pooping a lot finding their own little mini caves its very cute!
The clowns are much bigger than when you saw them last, only spotty but arguing over a specific cave as usual,and eating and eating along side the Bn's- they do not seem stressed or ill, other than the spots I'd say nothing is wrong with them other than my constant worrying over the spots. They have had it for over a week now the, spots are definitely lessening on most.
I can only give you my experience but over about a year and half ago, I had a couple of Otocinclus that I still have, a few days after they arrived they showed Ich, I panicked, looked everywhere for something safe for them as they are so prone to dying from transport and everything stresses them out,-they are catfish too of course so no scales, and their minute size cause they were juveniles when I got them- everywhere I went said there's no cure they are too small for meds, it'll kill them, they are already stressed from transport and just out of their own nature- they stress over everything when you first get them, so I did frequent water changes and put in "remember it's only my experience and it worked for me"- a few pennies in the water(4) one in each corner and fed them a lot of algae . I knew there wasn't enough Cu that would leech out as in the meds, and the Cu content in pennies is not so not 100% and it is released so slowly, the guppies I had in there also developed Ich, but over the course of several weeks, eventually every single fish recovered, I did not up temp. it was all room temp. but I don't know if it was the pennies but every single fish lived and the guppies also had fry during everything, the plants lived the Otos grew and eventually no more spots!!!
Coincidentally I have the tank with the fry juveniles and juvenile clowns showing Ich, also with pennies.(AND KEEP ADDING A FEW EVERY DAY!)
AGAIN SORRY ABOUT YOUR LOSS AND GOOD LUCK WITH THE BABES!!! I'LL UPDATE ON HOW MY SITUATION IS GOING MAYBE IT MIGHT HELP OUT IN SOME WAY.