FX cannot diagnose your son's condition or advise a course of treatment over the website. The best way to diagnose the problem is by seeing a doctor and having him/her take a thorough medical history, conduct a physical examination and ordering lab tests if needed. Once the diagnosis has been made then your doctor can talk to you and your son about treatments options.
There are many possible causes to your son's condition such as infection, allergic reaction and anatomical problems to name a few. Sometimes, oral lesions can be a sign of a more serious medical condition too.
If you live in northern New Jersey and would like to meet with a doctor from the Adolescent/Young Adult Center For Health you can cal 973-971-6475 for an appointment.