If you get diarreah, the best thing is to let it run its course and just get rehydrating fluids/salts/electrolytes (which should be consumed frequently). The packet mix can be mixed with bottle water and that's generally the recommended solution. If the diarreah doesn't come to an end after day 5, visiting a doctor is what some do. (Stomach aches are a separate matter, and if you are having those, then visiting a doctor should happen much sooner, like after day two if the pain is persistent.)

Stick to eating hot food only, drinking bottled water, and bottled water for brushing your teeth, and you'll likely be ok without falling all of the actions I mentioned above.