Hi there well to clarify a little bit or try to.
PDD is a term that is used more in America it basically means that he has ticked most of the boxes for Autism but not all.
Usually people who have aspergers are able to talk that is why they say this but it is not always the case.
In regard to the doc saying he could have high functioning Autism, over here in the UK high functioning is Aspergers really.
An IQ test will help as a very high percentage of Aspergers/high functioning Autism people have an above average IQ
Hope this sort of helps a little you could also visit my site http://talkautism.googlepages.com which has lots of info on Autism Aspergers and PDD
Talk Autism–The Positive Online Community