I have an upset tummy and vomiting what could it be from and when do i go to the doctor?

Uncertain - but: gastroenteritis is a frequent cause. The symptoms of Stomach Flu (Viral Gastroenteritis) can include: nausea, vomiting, headache, watery bowel movements (not bloody), abdominal cramps and a low fever. Medical assessment - for bloody diarrhea, vomiting blood, severe abdominal pain, inability to keep up with fluid losses (with drops in blood pressure) .or lack of sx resolution.