Hey Melissa,

It might not be food poisoning. It could be norovirus...
http://www.cdc.gov/ncidod/dvrd/revb/.../norovirus.htm

Food poisoning is caused by bad bacteria in your food. What did you eat at Mickey D's? Norovirus is what everyone calls the "stomach flu". It is a big misconception that the flu causes GI symptoms. Do you know of anyone you were around who was sick with the same thing?

To answer your other question, no, you should get rest. The longer you try to go on doing daily tasks (including exercising), the longer you will be sick.