Hope this isn't terribly bad netiquette but here goes:
Mrs Forgetful recently posted something really interesting on a thread in SN that might be useful for you to do with DS
Quoting the relevant part of her post...
"2 things i think you should do.
- Draw a 'WORRY' spider with your son.
Basically all this is is a large circle as the body with as many legs as he has worries....so on each leg write the worry.
This helps him to express his problems....and will help you get a clearer picture too. "
maybe that might help ds express himself?