I’m glad the Xifaxan is doing the job. You didn’t mention its astonishing price, so I’m guessing that in your circumstances that isn’t a major issue. I don’t think I’d call it a biologic, though. It’s just a GI antibiotic, with minimal systemic absorption.
ARe you doing anything for the diarrhea? Do you actually have urgency, or just looser stools? Adding some soluble fiber (*not* at the same time as the Xifaxan) might help.