Hello, My Son 18, Healthy Has Had Hives X5 Days

hello, my son 18, healthy has had hives x5 days ( Benadryl or Allegra) symptoms slightly better, tonight he urinated dark tea colored urine, no pain, bilaterally kidneys no pain, bladder palpitation no pain, but next evac was slightly lighter in color, but still some blood present.
hydroxizine 50 mg. for hives? I believe it's either from Benadryl or hive related