highcharts mysql json flags

I have a working Highcharts, where my data comes from MYSQL with a PHP query. Result from MYSQL looks like this:

[{"name":"Datum","data":["2015-10-02 07:51","2015-10-02 07:56","2015-10-02 08:01"]},{"name":"Temp","data":[20.3,20.2,20.2]},{"name":"Fukt","data":[48.6,48.5,48.5]},{"name":"Comment","data":["Basement",null,null]}]

I am measuring Temperature and Humidity on different locations and each time I change location I type in the name of the location as a comment to MYSQL.

Now i want to show that comment in Highcharts.

This is my Highchart PHP file

<!DOCTYPE HTML>
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html;charset=utf-8" / >
        <meta http-equiv="refresh" content="150">
        <title>DHT22</title>
        <script type="text/javascript" src="js/jquery.min.js"></script>
        <script type="text/javascript">

        $(document).ready(function() {
            var options = {
                chart: {
                    zoomType: 'xy',
                    renderTo: 'container',
                    marginRight: 140,
                    marginBottom: 55
                },
                title: {
                    text: 'DHT22',
                    x: -20 //center
                },

                xAxis: {
                    crosshair: true,
                    tickInterval: 250,
                    labels: {
                        align: 'center',
                    }
                },
                yAxis: [{
                    title: {
                        style: {
                            color: Highcharts.getOptions().colors[10]
                        },
                        text: 'Fukt %',
                        rotation: -90,
                        x:0,
                    },
                    labels: {
                        style: {
                            color: Highcharts.getOptions().colors[10]
                        },
                        overflow: 'justify'
                    }
                },
                {
                title: {
                    style: {
                        color: Highcharts.getOptions().colors[0]
                    },
                    tickInterval: 1,
                    text: 'Temp °C',
                    rotation: -90,
                x:0,    
                },
                labels: {
                    style: {
                                color: Highcharts.getOptions().colors[0]
                            },
                    overflow: 'justify'
                },
                },
                {
                title: {
                    style: {
                        color: Highcharts.getOptions().colors[0]
                    },
                    tickInterval: 1,
                    text: 'Temp °C',
                    rotation: 90,
                    x:10,
                },
                labels: {
                    style: {
                        color: Highcharts.getOptions().colors[0]
                    },
                    overflow: 'justify'
                },
                linkedTo:1,
                opposite:true
                },
                {
                title: {
                    style: {
                        color: Highcharts.getOptions().colors[10]
                    },
                    tickInterval: 1,
                    text: 'Fukt %',
                    rotation: 90,
                    x:10,
                },
                labels: {
                    style: {
                        color: Highcharts.getOptions().colors[10]
                    },
                    overflow: 'justify'
                },
                linkedTo:0,
                opposite:true
                }
                ],
                legend: {
                    enabled: false,
                    layout: 'horizontal',
                    align: 'center',
                    verticalAlign: 'bottom',
                    y: 20,
                    borderWidth: 0
                },
                tooltip: {
                    shared: true,
                },
                series : [],
                credits: {
                    enabled: false
                }
            }

        $.getJSON("data_dht22.php", function(json) {
                    options.xAxis.categories = json[0]['data'];
                    options.series[0] = json[1];
                    options.series[0].yAxis = 1;
                    options.series[0].type = "spline",
                    options.series[1] = json[2];
                    options.series[1].type = "spline";
                    options.series[1].yAxis = 0;

                    chart = new Highcharts.Chart(options);
            });
        });
        </script>

        <script src="http://code.highcharts.com/highcharts.js"></script>
        <script src="http://code.highcharts.com/modules/exporting.js"></script>
    </head>
    <body>
        <div id="container" style="min-width: 400px; height: 400px; margin: 0 auto"></div>
        <form action="comment.php" method="get">
            <strong>Kommentar</strong>
            <input type=text name="comment">
            <br>
            <input type="submit" value="Lägg till" /> 
        </form>
    </body>
</html>

Something like this https://www.dropbox.com/sh/t0t3f6lcstwq6m7/AAAtrajWgVndziwfE6REx26fa?dl=0

Anyone that have an idea about a text poping up inside the graph?