I agree about the chalk for acid. Tobacco I've never tried, adn the apples are very rich in pectin. Apple puree goes down soft and easy. It's a soft bulk in the guts after the rigours of the squits.
I also agree with the 24 hours no food, but you have to keep the liquids up. Even if it seems as though it's running right out of you, both ends sometimes, just keep sipping it.
The vast majority of babies ever born died before they were five years old because of dehydration. Plain water isn't the best, the salt +sugar stuff helps keep everything balanced while the body fights the biological war in your guts.
It's all too easy to spread infection around with poor hygiene, especially in a camp situation. If you have the buggit you caught it from someone/ something. Try not to keep it passing along.
The commercial immodium and the like work by kind of paralysing the gut for a little time ( really they just kind of slow down the muscular contractions of peristalsis ), I'm wondering if that's what the tobacco does too ?