When our DS (now 7) was three, his pediatrician recommended him for speech therapy. Whenever DS went to the doctor, he'd clam up and cry a lot. (He knew the doctor meant shots, ear irrigation, etc.!)

Anyway, we were mystified since we only heard an advanced vocabulary with a bit of stuttering at home...usually when we realized he was thinking and speaking at the same time. (I did this as a young child and recall being told to think before I spoke.)

So, we took him off to an OT for evaluation. The therapist said that he spoke at a Kindergarten level! She didn't understand why his pediatrician recommended we see her.

We got a new doctor after that.

Perhaps this is a phase like what our son went through. I think kids like ours have so many ideas at once that they have to sift through them to get out what they want to say when they are that young. Especially when they are tired or hungry or in DS' case-scared!