Imortant! – Link structure changed in WordPress 4.4.1?

I have WordPress 4.4.1 and unfortunately a couple of probles since…

The link structure of my site seems to be changed. Normally it’s http://xxx.be/2015/07/xxx/ but this doesn’t work anymore (so all my searches in google result in a 404 😮 !)

Now it only work’s when you go to http://xxx.be/xxx/

Please help me someone, very important! 🙁