Allergy Eyes

OK...focusing on Christopher, my 6 year old son, today...he has really bad allergy eyes. Took him to allergist and had skin tests and the only thing he tested positive for was cat. We don't even have a cat, so that can't be it. Took him on Monday for blood to be drawn to do RAST test, but haven't gotten the results yet. Right now he is on Allegra daily and just got off a course of steroids. Allergist wants to also put him on a nosespray but am hesitant to do that when we don't even know what is causing his issues. Oh, and also eyedrops and cortisone cream for around his eyes. Any suggestions???