constant screeching

Question
Hello there.  I just had a question as to why my lovebird recently started screeching extremely loud non stop.  He is going to be 2yrs old in August, is tame, and  is out at least 3 hours during the week and longer on the weekends.  I have tried to change him over to a pellet diet, per my vet but he will not take to that in any way shape or form.  Any help would be greatly appreciated as he is making me crazy with this new bad behavior.  

Answer
Try to figure out if anything has changed in his environment (besides his diet change) that might have triggered the screaming.

Here are also some other articles about screaming that should help you:

http://www.parrothouse.com/sf3.html

http://www.parrothouse.com/sf8.html  (written with cockatoos in mind- but most, if not all, of the information applies to all parrots)

http://www.cockatiels.org/articles/behavior/screaming.html

http://www.companionparrot.com/screaming.htm

I hope this helps.

-Maggie