Whenever I have a stomach bug, diarrhea or not, I drink lots of colloidal silver and then if that seems to knock out the bug or knock it back a ways I always follow with probiotics to help restore gut flora to healthy levels. Might be a good idea for you to do probiotics daily anyway, as gut flora might be an issue for you (but that is purely guesswork).
Sliced or grated apples left out until they brown usually works well for stopping diarrhea and if not, raspberry leaf tea will usually do the trick - so much so that you have to be careful or it will "plug you up".
Lots of other info in this article I wrote that may be helpful:
http://www.tbyil.com/Diarrhea.htm
I hope this helps and good luck!