When I followed up with my regular doctor, he suggested that perhaps the initial injection may have swelled up and hit my
sciatic nerve. (He said that if the injection had been directly to my
nerve it would have been quite painful, and I don't recall having pain during the procedure, just gradual numbness.) He started me on a course of prednisone for the possible swelling, and referred me to a neurologist. The prednisone didn't seem to help.