.
The pain. Though, possibly, it was two things combined.
The lessor additive issue is experimenting with resistant starches. The goal is to better feed various bacteria et. al. in the lower intestines. To do this, eating a small amount (think half a cup to a cup) of pasta, beans, or potatoes... cooked, then cooled. You can reheat those, but don't eat them freshly cooked. As well, raw potatoes, if you can handle those.