Gmail Spam problem

[Silly John Fatty]

I have this really annoying issue. A week ago I was in my Gmail Inbox and was checking my Spam folder. On one of the Email, I accidentally clicked "Not Spam". Since then, I've been receiving plenty of emails – that usually go to the spam folder – in my inbox. I mark them all as spam but they keep coming and they all come from different addresses, but you see that it's the same thing (they're all in polish).

What can I do? Thanks.