Or check out enterolab.com
and get the gene test for Celiac/gluten sensitivity, too. Don't have to be eating gluten for their tests. But the Prednisone will influence results of the stool test (but not the gene test) while you are taking it and possibly for as long as 6-12 months after.
But really, if you feel better off gluten, then why bother with tests and just stay gluten-free?