You CAG is still a baby and is probably using its beak to test things. They test with their beak to see how strong a thing is to perch on. To help them balance when they go from here to there. Greys have no hands so their beaks do all sorts of things hands would do. If you start playing with your grey's beak with your fingers don't be surprised if he nips you a little too hard as they do get excited and start to play a little to hard much like kids. As for the screeching, you'll probably had to give your grey a little time to forget about the vet visit. I don't stay within my fids' vision when they go to the vet, that way I can "save" them from the trials the "evil" vet put them through.