What Causes Itching And A Red Mark On The Waist Skin?

hi doctor, my husband is having a itching on his waist skin since last 2-3 days and today suddenly he had a reddish mark on his waist..so i jst wana knw that what is dat? my husband's age is 29 yrs and height is 6 feet and he was having some skin problem earlier in his childhood..