Question regarding a child

My son has enamel hypoplasia and despite being an EXTREME athlete-he plays soccer on 3-4 teams all year, 1 of which is at academy level and when he has a spare moment he is outside playing basketball or at the park playing more soccer. The issue is over the past 3 years his weight has begun to balloon. He eats a balanced diet not interested in juice or sugar drinks and has been under the care of the specialty weight and wellness team at our Children's hospital. He recently asked to be put on meds and since that started 6 months ago he has gained 20 lbs! The medication is topirimate. He is so miserable and tired of being bullied endlessly and said he feels awful in his own body. We have an upcoming appt. and I am going to ask for a referral for Ped. Endocrinologist. He is 5ft 142 lbs and his growth vertically has slowed to a crawl as his weight has been rising faster. Nothing was indicated in a full blood panel but it was not a fasting panel. I am at my wits end and my heart is breaking bc I don't know how to help him.