Hello there, I read your message carefully and understood your concern. I see your son has developed swollen nipples which disturb him even when just wearing clothes because of pain. Your son is 9 years old, so I can say he is a step away from puberty. Most causes of swollen nipples in children are not serious and there is not too much to worry about. First, make sure he has not hurt them with poking or squeezing them. Also, see if your kid is gaining weight which can make his nipples look swollen. If swollen nipples are associated with fever, discharge or redness it may indicate for an infection. Antibiotics are prescribed then. Also, in boys entering puberty, there is one condition that we must consider- gynecomastia with abnormal growth of breasts in males. It is because of hormonal imbalance and once the hormone balance is suited the swelling disappears. Usually, it persists for 12-18 months and then disappears. Also, skin infections, allergies or insect bites make create such disturbances. You can check his skin for such involvements. If the symptoms do not go back within a week, please consult with his pediatrician. Hope this was helpful. Dr.Albana