Why does diarrhea feel like dying? it literally feels like a massive burning, painful, nauseating, weakness sensation. does soluble fiber prevent it?

Consider the source: When we have the runs we loose electrolytes, i.e., sodium potassium, magnesium, and it makes us feel week and unfocused. That's why people are encouraged to drink lots of fluids--so they don't dehydrate in the process. Fiber is more of a treatment than prevention. Best to see your doc to find the source. Peace and good health.