Blank screen with year date after loading page

Hi i’m suffering for a while when trying to fix the problem with page.
The thing is that i’m getting blank screen with year (shows only -2018 on body) after loading page. But the problem is:
When I click any link from menu the page loads up well but this is happening right after it loads completely and i have no idea how to fix this and what is causing this.
Honestly I forgot this page and let it stay for a few months but i remember that it was working properly the time I left it. So I was thinking maybe thats because of wordpress automatic updates? I’m using child theme so it should be fine. I just want to know where to start and how could I fix this problem. Thanks in advance!

• This topic was modified 6 years, 9 months ago by djemm1996. Reason: clarification

The page I need help with: [log in to see the link]