I think food poisoning will usually occur with fever. I am not sure. My husband and I both got a stomach flu last summer. Talk about miserable when you live in an apartment with one bathroom!
Here is WebMd's run down of stomach flu:
http://www.webmd.com/content/article/5/1680_51287.htm
Can you call you doctor? The only thing that helped me was to take phenegran. It calms the stomach and has a nice sedative effect. He also said to avoid too cold water, sip room temp water. Hold off the gatorade unless it is diluted until your stomach settles.
I think food poisoning runs its course quicker. Hope you feel better soon!