My five year old son has developed an odd 'habit' with his eyes. When talking to someone or bored or when's he's meant to be listening/ concentrating - he flicks his eyes around rapidly like he is watching a light darting around the room (it's hard to explain!). He seems to be in control of it as will stop if we ask his too, and doesn't do it watching tv or very engaged in something. But he does it ALOT, it's like a nervous twitch and very noticeable. School think it's an anxiety thing, I think I agree, or nervous habit (though sort of similar). Any help?