What Causes Stomach Cramps And Diarrhea?

I've had what seems to be a stomach flu for over 72 hours, starting out with a 101F fever that broke the first night, one bout of vomiting, crazy headaches that are finally gone, dizziness that has abated,and nothing but diarrhea for bowel movements, and that 5-6 times a day (and through each night). While the aches and pains are also starting to fade somewhat, and I have a little more energy, I am still having intense stomach cramping and diarrhea, now with trace amounts of blood in it (bright red on the tissue, pink in the toilet). Do I need to get medical attention for this? Could this be something other than stomach flu or food poisoning? I have had some trouble in the past with stomach cramping and have some old Prilosec and Dicyclomine in my medicine cabinet, which is another thing that makes me question what this might be. Thanks so much,
Paula