Thank you for telling me… I'm not sure what I can do as I've seen this image everywhere without credit or links, and it would be time-consuming to email all of these people and ask them to give credit or take it down.. sigh.
Yeah. I commented on the picture on Pinterest and gave your Deviantart credit. I hate how Pinterest so rarely gives credit to the original image. That said, I know on Google Chrome you can right click a picture and click "Search Google for this Image" and it will show you all the places that picture exists, including your DA.
I actually did the Google image search to find the pictures you were talking about and I found a ton of uncredited uses - not only on Pinterest either - of this background. I guess that's what happens when you give high-res stock for free. :/