Gatorade is a quick way to replenish the lost water and salts. The cheapest way to get in is by buying the powder and mixing it up a litre at at time. Diarrhea Dr. Weil suggests you avoid milk and milk products, raw vegetables and fruits, bran, whole-grain cereals, sugary foods, spices, caffeine, and alcohol until the problem subsides. I have found oranges and apples, much as I like them, make it worse. The natural corking food I found most effective is rice.
Diarrhea combined with gas is a deadly combination.
Beano helps reduce the gas. If things get really bad, try a Depends pad for men. They will rescue you from small accidents. Make sure you carry a couple of clean ones with you. Giving up orange juice, my favourite food, helped a lot.