You need to sit down & think what is different since you brought in the new cage, food, candles burning, different cologne, perfume, deodorant, hair spray, washing detergent, fabric softener, room deodorizers, smoking, tobacco and/or recreational, pesticides.....
Do you use any soaps on him? How dry is it in your home...if it is too dry, that can cause skin irritation, plucking & skin mutilation.....
In the mean time, a vet visit or at least a through discussion with a vet should be made asap...and...if it's a good vet, they're going to ask you the above questions also...the plucking could also be a disease and/or parasites.....
How long have you had this bird...and none of this happened before the past week or so? You did completely wash & dry the cage before letting the bird in it? The cage timing is probably just coincidental, but everything needs to be considered until a cause is determined.....
good luck.....
