You might have gastritis. I’d suggest discussing it with your doctor. If that’s what it is, a longish course of an acid blocker (e.g. Prilosec or Prevacid) would probably clear it up. It most likely has nothing to do with your pouch.
As far as feeling faint, is it possible that you’re getting dehydrated? Are you peeing light-colored urine at least a few times per day?