Suggest Treatment For White Spot On The Tongue Of A Child

My son 10 month old son has a rare genetic disorder. He is primarily affected by cardiomyopathy and neutropenia. He recently had a really bad case of thrush that spread down to his esophagus and caused him to be hospitalized for a week. Four weeks later he had a small white spot that formed on his tongue. Within two days, the affected area grew to the size of a dime. I took him to his pediatrician and he thought that it looked like some type of scar tissue from a burn or bite. Because of the baby s history he gave me a script for nystatin just in case it is another case of thrush. It s been a week and now the growth has spread to the bottom side of his tongue. Any suggestions?