Your husband may be having fungal infection
.. Tinea cruris and corporis.
Poor hygiene,perspiration, wetness,soap,DM, immunodeficiencies....etc may precipitate or exacerbate the disease.
Tell him to improve hygiene , to take healthy food and to avoid soap bath.
DM,HIV and other diseases may be ruled out.Oral antifungal
like ketoconazole and local antifungal
like clotrimazole would be helpful.
Still, you consult dermatologist
I hope you got my answer.
Dr. Ilyas Patel MD