Nostalgia has been one of the worst symptoms for me! All of the symptoms are terrible, but dwelling on the past and things you can not change is torture. It must have something to do with the infection/overgrowth and how it affects your mind! I'm sure it is also related to the fact that the times I dwell on were during better days - when I was not sick (and I miss those days so much). But I also dwell on mistakes, decisions, embarrassing moments, etc... I didn't do those things as much before my illness.