A few years ago awful thoughts I'd struggled with my whole life suddenly ramped up in awfulness. I had no idea why I was having them and assumed there was something very seriously wrong with me. I googled like crazy trying to find other people like me. Eventually I took myself to my GP and explained some (definitely not all, I was very ashamed) of what I had been experiencing. He immediately said it was a form of pure O (as in the 'obsessive' part of Obsessive Compulsive Disorder), also called intrusive thoughts. I had a few sessions of online CBT but honestly having a diagnosis made a huge difference to my MH.
Anyway, I still have intrusive thoughts. I'm not traumatised by them any more. AMA.
Ps apologies if this has already been done. Had a cursory look but couldn't see any thread on this.