Have had diarrhea an pains in my stomach all day. I just let run it's course?

Perhahps? If you are having fever, blood in the diarrhea, prolonged vomiting or prolonged diarrhea, you may have a more severe problem. If it is just water clear or brown and the pains are not intense and none of the above symptoms, then observation, fluids (like gatorade) and rest may be all that is needed. Simple viral gastroenteritis is ususally self limited. If concerned, seek medical opinion now.