Need some answers

I can't stand to be around my grandson, even though I love him.  He talks constantly dragging on, talking randomly about all kinds of things nonstop.  Won't give anyone a chance to chime in.  Constantly asking questions, calling your name over and over again and when you answer, doesn't ask you anything.  He is constantly moving and messing with everything he can get his hands on, breaks everything he picks up, even new toys he gets.  He is frustrated very easily and angered.  On the other hand, he is smart, says things in a grown up way, and amazes me at how perceptive he is.

I think he needs to be tested for something, I don't know what.  Someone help me!