I get a lot of these horrid images. Mine are (I think) entirely anxiety based. It has taken me a long long time to realise that because they often flash through at times when I don't think i'm in the least bit anxious....but I definitely am. They increase when I'm anxious and in a low mood. Sometimes I get to the point where they're so constant they're more an irritation than anything else, like having intrusive bad thoughts (which I guess they are but visual ones) but at others they can be so bad they make me catch my breath (which can be fairly hard to explain to people).

Have you tried noting down both the images you get and when you get them and trying to figure out a pattern? Other than that I'd try and not get to apprehensive about them...just because you think these thoughts doesn't mean you'll carry them out. I found once I realised that I could get through a day being bombarded with them. Although I understand how difficult and scary it can be.