Disease ?? what is it what to do??

[xanth]

90 gallon display
3 power heads
Bio wheel
Protein skimmer
75 lbs live rock
65 lbs crushed coral
2 heaters
260 watts pc x 2 for 520 watts light
All water tests are good

Dose and one have suggestions on how to determine what is going on with my display tank and fish
My sixline wrasse was injured during shipping he had a white cauliflower growth on him but was healthy; in fact I had two sixlne wrasse and had to remove the other because the injured wrasse was so healthy/ active/ aggressive. Then the aggressive one was injured by being sucked up into a protein skimmer, I was able to free him and all he had was some fin damage and his colors were dull. 3 weeks latter (3 days ago) he started twitching, wanted to be in high current areas of tank and his eyes started to bulge. I removed him from the main tank did a fresh water dip (it looked like little white/clear scales fell off of him) and then put him in a qt tank what should I treat the wrasse with?

The only thing different I did in the display tank was skip a weekly water change

Also I have the following in my display tank
Fox face lo seems ill had some slime coming off of him
Sailfin tang he seems fine
Clown fish he seems fine
Lawnmower blenny hard to tell he always hides
Xenia it seems to be doing great
Two feather dusters seems to be ok
I lost a bulb anenoma last week

Do I need to qt everything? (My qt tank is 10 gallon if I do have to qt do I need a larger setup to avoid overcrowding/ ammonia spike)

How do I treat the inverts and live rock? Do I have to tear down the tank? Change salinity? Change temperature?

Any suggestions will help