Fin Rot & Pop Eye

[ponokareefer]

I have a male swallowtail angel that has been in quarantine for 4 weeks now, and was going to put it into my main display tank, but over the weekend, it developed a pop eye & it's fins are slowly "rotting" off. I initially thought a yellow tang was nipping it's fins, so moved the yellow tang into my display tank after 3.5 weeks. After the move, the fins have continued to erode off.
From what I have read online, it seems that the fish most likely bumped his eye, causing some minor swelling and whiteness. It is likely to go away in a week or 2.
Also, from what I read, the fin rot was caused by poor water quality/stress in the quarantine tank. From what I've read, they recommend putting the fish in the main display tank to reduce its stress from the quarantine tank.
Does anyone have any similiar experience with this? I am hesitant to put this fish in my main display with the issues it is having. Prior to the weekend, the fish was eating very well, and swimming around fine. There is a much smaller female swallowtail angel in the tank with it that is not displaying any issues.