With hurricanes and tropical storms having just passed through or on their way, many people with health conditions are having to quickly evacuate, which involves making quick decisions about what medical supplies and rations to bring with them. CDC has helpful guidelines to help with this. My post about packing for vacations has some tips that are also relevant to evacuation packing and disaster prep.
Remember that with diarrhea, you may need more water than the typical gallon-per-day rule of thumb (and don't forget food and water for pets!)
Take care and be safe!