Celiac disease is a food intolerance to wheat, oats, rye and barley not an
allergy - a food intolerance.  It is not an allergy.  Food intolerances and
allergies are different.

The medical  test for celiac is first a preliminary blood test where the Dr.
(a Gastroenterologist) tests your antibodies. (IgA, IgG and endomysial
antibodies).  If they are positive, then the doctor gives you an endoscopy
for a biopsy of your intestine.  This is the only 100% gold standard for
diagnosing celiac disease.

Celiac disease affects the villi in your intestine. The villi in your
intestines are hairlike projections that look like a shag rug.  If you have
celiac disease the biopsy will show that the villi are flattened instead of
being straight up.  (there are other things doctors look for, but this is an
over-simplification).  This means that the food is not being absorbed.
Celiac is a malabsorption syndrone.

Some people with celiac disease have lactose intolerance temporarily - some
permanently.   For those with temporary lactose intolerance, it means that
until the villi heal (by having no wheat, oats, rye and barley) you can't
tolerate lactose.  In some people even though the villi heal, you can have an
additional intolerance to lactose.

I was one of the ones who had a temporary lactose intolerance.

Does this help?

Jane