@Ok, I see it now, I even warned her about oats, because some/a lot of celiacs can't eat oats. It threw me off because she mentioned whole grains.
@CommandoMum check the whole grains you mentioned in case some of them have gluten or a related form of gluten like oats do have gluten, it's just in a form that isn't as likely to bother you but still can. Soy even has a related ingredient that can bother some celiacs. Plus a lot of diabetics react badly to rice, whole grain or not. I am a type 1 but I know it plays havoc with my BG's. But I am still thinking you might try skipping grains to see if it helps for a few days.
With celiac you can just get really sick, it strips your ability to properly digest food if it went on too long. That alone can make you feel bad and it sounds like you have some other issue(s) going on. I hope you find out soon so you can start feeling better.