My Husband Has An Almost Constant Hive Like Rash That

my husband has an almost constant hive like rash that starts on his buttocks and thighs and works its way up his torso in smaller patches and in severe breakouts (almost daily now) they get on his eyes and he has visible knots under his skin especially in his hands and forearms and head Any ideas? hes been to his regular dr. and referred to an allergist that has referred him to a dermatologist for a biopsy?