Based on your dentist's advice and the clinical presentation, undergoing a Lingual Frenectomy/toungue tie release is highly recommended.
The restriction directly impacts the mechanics and function of the lower jaw and the tongue. Most frequently faced issues are associated with Speech, swallowing and chewing. Some of which you must have experienced with your son too.
Next Steps
Schedule the surgical procedure after the detailed clinical evaluation.
Health Tips
This is a minor and a routine surgical procedure and you will just have to follow the instructions provided by the dentist post-op.