In the last 5 weeks, I have had three episodes of nausea, vomiting, diarrhea, and chills that came on suddenly. The first time it happened, I felt ill (extremely tired/ nauseous) for the whole next day. The last two times, it only lasted a few hours. The first two times, it came on in the middle of the night (4:30 and 2:30am respectively) and the third, I suddenly felt sick at 10pm. I am not pregnant (I had a recent period) and have no known food allergies (not can track a specific food I ate all three times, except that I ate fish all three days--but different kinds of fish). What could be the possible causes of this? Is there anything I can do before I see a doctor in 2 weeks?