Severe diarrhea
Diarrhea is one of the most common symptoms of norovirus. Diarrhea is persistent and often sudden bowel movements. Diarrhea caused by norovirus is watery and bloodless [9]. If you observe blood in your stool, you probably have another health condition.
The suddenness and frequency of the watery stools can cause your rectum to feel sore, even though no damage has been done to it. Fortunately, this symptom usually does not last more than three days. See a doctor if you have symptoms that persist for longer than expected.
Diarrhea that lasts more than three days might not be norovirus. Many other gastrointestinal problems such as colitis can also trigger diarrhea.