I've posted few times over past year with ongoing issues that seem to be down to hidden/sneaky gluten and/or other food/grain components that might be making me ill (e.g. lectins).
All tests have been cancelled owing to lockdown and have been waiting almost a year now for Small Intestinal Bacterial Overgrowth (SIBO) test. Have now gone private at princely cost of £250 for SIBO test. It's a breath hydrogen test, and apparently SIBO may be explanation for refractory coeliac symptoms.
Will keep everyone updated (lucky you!!!) as to how it goes and if it's worth exploring also. I'm going through the Functional Gut Clinic in Manchester (who knew such a place existed?!).