Hello @azdrew,
I'd like to add my welcome to Jamie's, as well; any infections in the gut can be so tough! You will notice that I moved and merged your message, as we have a few members on Connect with similar symptoms, and I hope they will join this conversation.
While researching the internet I came across this article in one of the scientific journals: http://wb.md/2hNQBcj which details SIBO, diet triggers, and carbohydrate malabsorption.
Allow me to also introduce you to @acres, @sprinklergal66, who have been on Xifaxan (Rifaximin), and may be able to provide more insight about this drug, in addition to the valuable information offered by @lateacher.
@azdrew, have your doctors ever suggested fecal transplant, since that seems to be a growing therapy for intestinal infections?
I'm not sure fecal transplant is available via the NHS in Britain. But I have an award winning consultant - I'll ask her when I see her.