Dear Ruth Anne, thankyou for your question.
I am really sorry this has happened to your 6 yr old Bunny.
Bunny's are sensitive to humidity and it can be difficult to even know your bunny is having problems. Generally they become really quiet when they aren't well. Because Bunny wears a fur coat all year around it's important to keep them cool.
Obviously when all of this construction took place it let a lot of humidity and exposed mold into the home. A Very toxic combination you could not have understood would have caused your bunny to become so sick.
I need to share the following with you so it can help a future bunny.
Educate Yourself before Bringing Bunny Home - Mold and Mycotoxins - RabbitsNmore
More is explained here:House Rabbit Network Press Release
Again,I send my sympathies but honestly I really hope you get another bunny because you are clearly a good owner who really loves them.
Thankyou & God Bless!