How Can Urticaria With Swelling, Breathlessness And Dysphagia Be Treated?

Hi ive been breaking out since december only thing that changed in my life is that I started a new job at a call center. Only that actually makes the hives go away is prednisone. Ive been all types of antihistamines nothing works. Thursday at 2am i swelled up and has difficulty breathing and swollowing went to the ER and they said its angioedema a severe case. I've never had any heath conditions or allergies. Im 26 and tired. Been to an allergist all my labs came back fine. What do i do now?