Hey EC, my sympathies, that's a hard one. It sounds most to me like what are called "intrusive thoughts." That might be a good google start for you, as it is a clinical term. For me, it's connected to PTSD, but I don't suppose that is the only thing they connect to.

Have you heard of DBT? Dialectical Behavior Therapy? I'm in a course currently and find it to be the most useful information I have encountered yet. It seems centered around the concept of mindfulness, and even uses much of the buddhist teachings in that regard. You can read quite a lot about it right here on this site by clicking on the "resource directory" link in the blue bar at the top of the page.

Hope it's helpful.

sqrl.