I am very surprised and relieved to see so many people on here with the same symptoms. I just wanted to share also. I think the more people share their experiences the more solutions we may find.
Mine started about 12 years ago. All of the experiences have been the same except frequency. I could go 6 months without an episode and then get them for days and weeks in a row.
My episodes start with a sound or sight of something that triggers a deja vu like feeling. It usually has some familiar song or words said that seems the same every time. Just like most of you I have tried to remember what was said or the song but after the episode it is lost. I have also tried to write it down but in the process I get confused and can't seem to remember what it is. I also seem to get a feeling of doom with it almost like the world is ending or something. (that is the weirdest part) It ends in nausea and I tend to be very tired. My girlfriend knows when it happens to me because I tend to lick my lips and seem to appear distant.
I have always felt like this is unexplainable to a doctor and have never tried. Especially since I could never make it happen. It seems so random. Now I may have to bring it up especially since it has been more frequent lately.