How can we tell if we are having d from our IBS or if it's the stomach flu? I think I might have the stomach flu because I never get sick with d in the evenings and shortly after I got home from work last night I had d. My stomach is rumbling again today. I don't know. Maybe it is stress. I did find out earlier this week that my grandmother has pancreatic cancer with 2 months left to live. Who knows.