I'm going crazy with node pg module, getting 'too many clients already' error.

My app.js file for example, manages some routes in which I query some data to postgres. app.js looks like bellow:

//First I create a client

var client = new pg.Client(connectionString);

// Then I use that client to every routes, for example:

ContPg.prototype.someController = function(req, res){

    client.connect(function(error){

        if(error) return console.error('error conectando', error); 

        // Need to close client if there's an error connecting??



        client.query(someQuery, function(e,r){

            client.end(); 

            // Here sometimes I dont end client if i need to query more data 

            if(e) return console.error('error consultando', e);

            // Do anything with result...

        })

    });

}

As I said I use that client for all routes in file pg.js, but in other files with other routes I do the same to connect to postgres (create client and use for all routes that manage that file)

Questions

Is something wrong with my code? I ended wrong client connection?
If there's nothing wrong, what could be causing 'too many clients already' error?

Thanks in advance!!