You need to see a doctor. It could be a
virus,
bacteria, or even a parasite if you were drinking contaminated water while camping. Adults don't get fevers very easily, so this is serious. Keep to the BRAT diet to help stop the diarrhea--bananas, rice, applesauce, and toast. Milk products don't feed the bacteria in your stomach, but they're best to avoid because fatty things can make you feel sicker.