How Can Tardive Dyskinesia Be Treated?

My 25 month old son sticks his tongue out when he is concentrating. He has been doing this since he was a baby and he used to do this when he is idle or sleepy or when he is concentrating. What do we do to stop it. We tell him repeatedly to put his tongue in...he puts it in and it sticks back out in few minutes. This does not happen when he is busy or occupied with something...he also says few words fine. Any ideas or suggestions are welcome.