What kind of "specialists" has he seen and how many? To truly rule out Autism Spectrum, you need to have him evaluated by an Autism Specialist. There are specific tests, like the ADOS, that THEY use. No one else is truly qualified. You should ask the school if they have one or have access to one.
What Keista said as well as academic, psychological, behavioral, emotional, language processing, expressive language, and receptive language evaluations are definitely things they should look into. What specific tests they use would be up to them but make sure they are addressing ALL these areas. Since he's only 4 the other areas I would normally recommend (reading, writing, math skills) may not be appropriate yet.
