Rose Breasted Cockatoo suddenly is fearful of me

Question
hello,  I purchased a Rose Breasted Cockatoo in May.  He has been sweet and loving until this past week. He would talk for hours.  But now does not talk as much.

When I go even near his cage is panics and flaps and trys to escape.  when I take him out he panics and flys and/or runs across the floor.  He bites me hard!  Other family members he is still sweet to.  

I can't think of anything different that I have done.  

He is 18 months old right now.  He was about a year when I got him.

Answer
Hi. Thanks for your question! Initially from what you said, I am wondering if your bird is not feeling well.  Any time your bird shows a major behavior change, such as discontinuing singing or talking, usually this is cause for concern. When birds are ill, they become quiet. This is an instinct because in the wild, they would not want to draw attention to themselves, especially if they are sick. This would make them an easy target for predators.  
Is he eating less/more? Do his feathers look matted? Is his tail bobbing? Look for any other signs of illness. Illness is usually the only reason that a normally "chatty" bird would go mute.
You say that he is being sweet to other family members. Is he letting anyone handle him? Sick birds usually do not like to be handled.  
If it weren't for the change in his vocalizations, I would wonder if it was just a reaction to you...perhaps wearing something that frightens the bird (i have had my bird for 15 years and he still gets scared of me when i wear my glasses, if i wear a t shirt with something on it that scares him, if i have fake nails, if I'm wearing anything different on my hands or arms). Sometimes that can scare a bird.
However, if this is not the case, I would look for any signs of illness. Birds usually hide their illnesses very well so that "predators" will not know that they are sick (instinct).  Like I said, lack of vocalizing suddenly is usually your only cue. Unfortunately, many bird owners overlook this and don't realize the bird is sick until it is too late. With birds "too late" is usually the only time they start acting sick. I would look for any signs of illness and make a vet appointment. Birds just don't "stop" making noise for no reason. good luck. let me know how it goes. alicia