I'm sorry but I disagree with most of what is posted here even though I'm rarely a fan of CW and am definitely in the "you know your body better than any doctor" camp.
You seem very vague on the most important question which is why did you book an appointment to go and see a gasto doctor in the first place ?
1 - If the answer is that you have had various problems that are gastro related over a long period of time hence you trying so many different diets then that is a whole different post to if the answer is that:
2 - You have always had great digestion and problems have only started occurring since you altered your eating to PB
So I don't think anyone can comment on this until we actually understand the issue, because imo if the answer is 2 then I don't really understand why you made the appointment - and I don't think anyone can fault a doctor who says that an eating plan is not agreeing with you if you have made an appointment to see them because the eating plan you are using is not.