Thanks for posting your query.
Your husband must be suffering from chronic urticaria
. most of the cases belong to idiopathic category. That is difficult or cause not known. He must take anti histamines
or the latest non sedative like levo cetrizine
one tab per day and if he under good control which means rash
free for 24 hrs. he can continue the medication for few months before he stops. he may not need for more than six months.
there is nothing to worry.
meanwhile you can avoid egg, fish, fish products etc and check if it helps
have a good day