OK, other than the cast iron I would put money on dairy being a problem. Lots of celiacs have trouble with dairy at first because the part of us (the villi) that is damaged is the part that digests dairy. Get your new pans and go completely off dairy for a while and see of that doesn't do the trick. Most of us get dairy back after we've healed (six months to a year).
Have you read the Newbie 101 thread in the coping section? It's full of all sorts of helpful information about cast iron and dairy and cross-contamination and more.