The last six months or so I ve had sudden unexplained nausea. From about May to Sept , a couple times a month. Then from Sept through Nov an average of about once a week. Now in December it s been basically daily, and usually several times a day. Suddenly, without prompting by anything I ve eaten or done. Unexpected, and unexplained, lasting anywhere from about a couple of minutes to about 10 minutes or so, then subsiding for a few hours until the next episode. I have a prescription now for prochlorper 10mg tabs prn which help but I still am mystified and concerned....Any ideas?