My son had tuberculosis when he was 9years old. his coughing however sounds really bad. is it possible for tb to have a relapse?

Tuberculosis: Although the first thought may be a reinfection, it may not be probable. Your son is probably as healthy or healthier than his peers (malnutrition is often associated with tb). He needs a consultation with his primary care physician or pulmonologist. If necessary, a chest x-ray maybe indicated. My feeling is that he probably just have a bad cold (or whooping cough).