I totally understand. We put in a lot of work with our chickens and I don't like to lose any either. When I lose a chicken it never fails it's always my favorite. Hope you can find a solution to this problem and right quick too.
It doesn't appear as red, did the chick get pecked in the eye by another chick? After the last swollen eye thread I looked at your chicken looks wonderful. Someone will come along shortly and give you some good feedback. Best of luck!