repeated behavior, facial "tic"

Our son just turned 10.  Since he was very young he has alway had some subtle behaviors he felt compelled to do like following a pattern of touching the corners of a table when he would sit down, or feeling a strong need to touch a part of his body in a sequence like his knees when seated.   This stopped for a while.   At 8 yrs.  he began quitely coughing and clearing his throat during the day. His doctor prescribed a course of medicine and an expectorant which did not help. This has been going on for about a year.  At 9 1/2 he started to sniff very loudly all day long as though he had flem (phlegm) he was trying to clear from his throat.  His doctor said he had some minor irritation in his throat and prescribed medicine which did not help. This has turned into a very forceful nasal throat clearing and caughing.  The past 3 months he has started forcefully to pull air into his stomach and releasing a long belch. ,He also is straining his neck muscles and pushing out his jaw.  The last week he has started to throw up during the day when this belching behavior was more intense.  He has no control over this.  Occasionally when he does something to occupy his thoughts like reading or playing a electronic game it quiets for a short moment, then starts up again.   It is upsetting to him that it draws attention to himself all day long.  It's very stressful to be around this behavior and distracting to classmates and in public places. It is beyond his control. And seems to gets worse if asked to try to control it.  We are living in Southern China which is heavily polluted and we think this may be a contributing factor.  
We hope someone can help.

[LRM1021]

The various behaviors you describe all sound like anxiety disorders-- OCD, tourrette's , etc.  The sequential touching is OCD -- pretty classicly, and the throat clearing and coughing are vocal tics -- a form of Tourette's Syndrome. These are both anxiety-based disorders. People who experience them are experiencing an unusual amount of anxiety in response to situations that normally do not provoke anxiety.

Your son needs to be seen by a child psychiatrist who can evaluate these behavior patterns, as well as your son overall, and prescribe the appropriate treatment path.