In the past week, after having no crawl errors on my website at all, I'm now getting the following showing up in Google Webmaster Tools after some of the pages:
[fullURL]?2016-jun-764.html
The date is the same on them eg "2016-jun" but the number before the ".html" changes on each entry.
Also, if you take the full URL, even with the "?2016-jun-764.html" at the end, the correct page on my website comes up - it doesn't generate an error.
Has anyone else seen these, and if so, do you know how they have been created and how to stop them?