for several years I have had occasional giant hives at various joints with a lot of swelling and itching; I used toget them on my left jaw and one time went to the emergency room because i had trouble swallowing, and my palms itched. One time a doctor told me that the sun had caused giant hives on my upper arms near my shoulders. What causes this? At the present time, my right knee is swollen, red and itchy, have had these things happen for the last 20 years. i have hypothyroidism and severe COPD( , 3 LPM 24 hrs. a day.