What is it? I have fever (better by: drinking fluids, rest) (worsened by: dehydration (fluid loss), exercise or physical activity) (severity: moderate) and diarrhea (severity: severe).

Get evaluation. I generally define fever as 100.5 degrees Fahrenheit or above. It depends on how long the fever has been going. If you have been having fever for less than a week, it is most likely viral or bacterial gastroenteritis. If severe diarrhea with dehydration and lightheadedness, get seen right away. If the fever has been going a week or more, you should definitely get evaluated as well.