Suggest Treatment To Get Rid Of Surgery Scar

Hi doctor ! My son had a surgery two years ago of a heart murmur ,and the scur is really thick and long .. i try so many scur remove creams but i dont see any changes .He is now 5 years old and it kills me when we go to the beach how the other kids look at him so please tell me what should i do ? Is he too young for plastic surgery or is it gonna go a way ?