While echolalia is common in children with autism, that alone is not sufficient to make a diagnosis. I would suggest that you go try to identify a hospital in an urban area where they specialize in diagnosis of children with autism and other developmental delays. A comprehensive evaluation by a team of specialists will result in diagnostic information as well as treatment recommendations. You can then take these recommendations to your local school system.
The most effective treatment for children with autism is early intensive behavioral intervention. This means that your son should receive 20 hours of direct teaching in language, social skills and self-help skills. Services can be provided by the public school in your area. You may want to look for behaviorally trained professionals to supervise a treatment program by checking www.bacb.com for a person in your area.
Echolalia is related to autism. I don't know if you can have echolalia without autism. My son is echolalic and he also can put together his own speech as well. He is age 7. It is very good that he is speaking. Does he also use Delayed Echolalia eg. pieces of dialogue phrases or words from TV or films? The Speech and Language Therapist should be able to tell you more about it. I would specifically be asking for a Speech and Language Therapist who also has experience of autism.
Does your son mix up his pronouns eg. I, me, you, yours, mine, us etc.
What is your son's social interaction skills like?
Are there things that your son is good at eg. puzzles, lego, pattern recognition etc.
Are the people/professionals, who have seen him so far, experienced in diagnosising autistic spectrum disorders such as PDD/NOS, Autism, Autism Spectrum Disorder, Aspergers, High Funtioning Autism etc. If not I would be specifically asking for a referal to a centre/unit that does.
Google DSM IV for autism and read through the diagnositic criteria. Does your child have diffficulties in the three areas it mentions?
What type of school does your son go to and what country are you in?