5 month old cockatiel WONT WEAN!!!!!!

[crystalchik]

I know this isnt a chicken problem, but I dont know where else to go! I have a little cockatiel that is almost 5 months old now and he REFUSES TO WEAN!!!!! He has refused to pick up any solid food. I tried going off feedings little by little and eventually he almost died because he got dehydrated, I had to revive him with Pedialyte!
I am trying feeding only twice a day but he screams bloody murder if do. He is still skinny and I am feeding him 3 times a day. I have bright colored pelleted food, seeds and toys in his cage and because his nest mates have already grown up, weaned, and been SOLD, I have had to move him in with my next clutch of cockatiels..They are starting to wean and still, he is not.
THe other thing I noticed is that he doesnt fly much, if at all. And when he does, any food that I have given him, comes strait up. Or any stimuli at all for that matter. If i pick him up or if he puts his head down, the food roles right out of his throat. He can only keep 15cc down if he is not touched, any more comes back up if he even moves.
This doesnt sound right to me, and I no one else can figure out what is wrong. Any ideas or suggestions?
I would appreciate ANYTHING!!!
Thankyou,
Crystalchik