Diarrhea isn't fun anywhere but definitely makes you feel helpless when you are in a country where you don't know what to take.
The first reaction Mr. Rant has when I'm urinating out of the wrong side is for me to drink a Yakult. Since it has all the healthy bacteria my body would be obviously lacking in that situation it seems like good advice. I'm sorry but I always go no on that one. Yakult gives my healthy intestine the poops, goodness knows what ass fire I'd be dealing with when under the weather.
The next is Floratil. It's a pill version of the healthy bacteria. I totally take these but keep in mind that it usually takes a couple of days to work, aka when you diarrhea would have stopped anyway.
For those in a state of immediate need of corkage, the medicine you are looking for is called Imosec. This will cork you right up (especially if you take two). While I am a firm believer of letting the watery times roll, when you have to have all calls forwarded to the bathroom it may be time to step in and bitch slap Mother Nature.