Pda diagnosis.

Hi I've a son diagnosed with asd. As he's going to senior school in September and school is where 99%of his meltdowns happen, I'd like a more detailed diagnosis as I would bet my house on it being pda. I'm off to see the consultant for a review tomorrow(I've left it late I know) and I know they don't diagnose pda in our area but want as near a diagnosis as possible so that senior school (srp) knows from the beginning. Any tips or advice would be more than welcome xx