Loop in thumbnails from the same custom post

Hey. I´m switching from categories to custom posts, and on my current page I´m looping in thumbnails from the same category as the one displaying on single.php. That is, on single.php i loop in my content and below the content comes thumbnails from the same category.

I would like to do the same thing now, but with custom post instead. I´m not much of a coder, so I dont know really how to change my current code to check for the same custom posts instead. Maybe someone can help me with this?

My code looks like this now:
http://pastebin.com/mnfGQitC

I just want to change it so it looks for posts in the same custom post! Hoping for some helpful soul out there 🙂