This kind of a rash
can be for various reasons. To diagnose it propery a visual inspection is reqired. However the common reasons are sun exposure, contact allergy
to some clothings/ wearings and seasonal sensitivities. You should keep the area moist with generally available skin creams specially the ones with vit E & aloe vera
. Use glycerine soap and resist the itching . application of Ice is better then mangos. Keep the area covered with loose clothing preferably made of cotton. You may need to visit a skin doctor if symptom persists over 2-3 days.
Hope your husband does good soon.