It seems that you may be having idiopathic urticaria. As you got blood tests normal and found no cause, the urticaria is labelled as idiopathic urticaria. Take fexofenadine
in morning. Take hydroxyzine
HCL at night. If poor response, add steroid in tappering dose for short period. Reduce anxiety. Any treatment, take under supervision of dermatologist
. I hope you got my answer.
Dr. Ilyas Patel M.D.