Do upset stomach and diarrhea have anything to do with a seizure or is there a flu going around seizure free for 16 years after having 2?

No and no: Upset stomach and diarrhea are oftern indicative of gastroenteritis that is generally viral. If you had a "seizure" in your sleep 16 years ago it would be important to know how this was documented and whether you have had imaging studies of your brain and an eeg. Sounds like it might be helpful for you to see a neurologist and perhaps a clinical psychologist or psychiatrist. Good luck.