I guess he needs referring. Argh. Just been through all this with ds1, had ds2 checked about a month ago and seemed fine. His squint has developed since then and it's noticeable (people have pointed it out). .
(Sounds pathetic but I can't remember who I go to in the first instance; seem to remember with ds1 I went to the "wrong" people first and got shoved from pillar to post to start with)