Powder Brown Tang Losing Color?

I have a Powder brown tang in my QT tank under hypo salinity treating ich.. he has been in there for about 9 days now. His ich spots have vanished off his body and gills but he still has a few spots on his fins.. i am not sure if its ich or what it is.. they look like little things that are inside his fins not on top of them..

Anyways.. he does not look brown anymore he looks grey and yellow could this be because he is not happy in a 20g QT tank with hypo or is he showing signs of some other sickness?

 

also the white face looks pink.

 

Whats its eatin habits in the QT..??

 

feeding frozen brine and 2 inch by 2 inch piece of seaweed sheet. there is also a small tang in there as well who looks fine

 

Get him out of there NOW and put him back--I work at a fish store and when the powder browns start to look like this, they dont make it too much longer--it is caused by stress--dont worry about the ick--feed him healthy and he will recover on his own--I have a PB and small portions of ick come and go on him--he is the only one in the tank that is like that--feed garlic and nori, but get him out!!!!