Another disease to consider is lymphocystis. This is a viral illness and is often induced by stressful situations. If this is what your fish has, you can expect the white lesions to increase to larger, cottony spots. This is best treated by minimizing stress and optimizing nutrition. If the spots remain very small, like grains of salt, then it's more likely ich. Either way, it's good that the fish is in quarantine. Keep us updated on the progress of those lesions.