I certainly can relate. I get phrases stuck in my head, that just keep repeating, sometimes for days. I also have OCD, so I guess it's part of that. The only thing I've ever found to help is if it's at night I write down the phrase or word in my diary at the back. I can then tell myself it's safe to calm down in my mind because it's written and won't be forgotten. Some of the stuff I've got stuck on I didn't even understand what it meant, I had to look up some of the words. I don't know where it comes from.

Sorry I can't say more to help!