I have an bare eyed cockatoo and I just finished feeding her this morning and i notice that she spit up some formula it came watery out of her mouth she is 4 months old please help.
Older baby bird spitting up after feeding by: The Avian Vet
At 4 months she should be weaned and not being hand fed. Her crop is trying to shrink but hand feeding over fills it and she regurgitates.
There are other causes so I recommend that you have her examined by an avian veterinarian and check for other causes such as bacterial infections, yeast infections, avian borna virus and even PBFD.
I suspect you are going to have a difficult time weaning this bird and you will also experience some significant behavioral problems in the future. I am happy to set up a phone consult with you to discuss this.