Below are some products that have helped us along the way when we've gotten sick to our stomach, maybe they can help you to.
When we took a day trip to Monaco last year after a couple of days of rich, delicious, and filling French food, I got stuck in a train car with no air conditioning on a 100 degree day. By the time we arrived, I was not feeling well at all and immediately got sick in the bathroom at the train station.
To try to save the day and not ruin it for the rest of our party, I went into the first pharmacy I saw and described my symptoms. The lady inside sold me these chews, which did wonders for me. I ended up buying a case and bringing them home. From now on, whenever I get a really upset stomach, I reach for what we call to this day "Monaco Mints."
Of course, when you got it real bad, you just need it stopped as quick as possible. Imodium is what you need for a real bad case of diarrhea. If it doesn't stop it, then you've got real problems. Of course, the resulting constipation is not real comfortable either but it beats living in the bathroom.
These three products are tried & true by your World on Wheels team and have the added benefit of being able to travel in your carry-on because they are not liquid. Give 'em a try on your next extended adventure.