I'm in the middle of this mystery myself. As far as they can tell, it's nothing cardiac which is good. The second most common culprit is gastric reflux/GERD which is, honestly, a distinct possibility. They're doing an upper GI series in a few weeks. In my case, don't think it is at all anxiety related (definitely could have been at some other point in my life -- just doesn't make sense now that anxiety really isn't an issue anymore). My gut suspicion is that it is menopause-related because I've also developed visual migraines at the same time. Menopause -- the gift that just keeps on giving. LOL! Doctors aren't too terribly concerned that it is anything dangerous; neither am I. But it is distracting and a bit of a nuisance, and they agree if we can at least figure out what is causing it, even if completely benign (and most likely is), there are things we can probably do to get it to be less annoying.