I have the same problem. I'm 46, live alone, have suffered from depression and more recently anxiety, and very recently was found to have a benign brain tumor. Over the last few years, my parents and a best friend passed away. I'm worried about getting older and getting sick and not being able to take care of myself... and I'm terrified of dying. I think about these things every day. I can't get them out of my head. I've never been diagnosed with OCD. Perhaps I have it?