I don't know if taking "PB only" is or should be a sustainable long term treatment plan and I did not mean that. My point was that if you take PB 3-4 doses for a few days the rumblings are quite likely to stop. I would actually think even one or two dosings might cause a cessation of symptoms. In the past I have used PB liberally and successfully as a supplemental treatment when everything else was not working, and I was suffering symptoms including those you have described. For any kind of "upset stomach", I have found immediate relief from this ages old bactericidal standby.
Pepto Bismol is like a relief pitcher in baseball- the best relief pitcher in the bullpen, who comes into the game when the starting pitcher or initial relievers cannot get anyone out. I have exactly the same philosophy in using it.