Hi! I Just Discovered That My 14 Year Old Son

Hi! I just discovered that my 14 year old son has what feels like a large bump on the center-back of his skull. It feels hard like bone. It's about an inch wide, and rounded- colorless, no swelling. It is immobile and his scalp passes over it as if it were bone. . It is colorless, painless, and causes no problems.
He does have enlarged lymph nodes on both sides of his neck- One lymph node was removed & Biopsy done 3 years ago to check it out= Benign. The doctors at that time said he "just has larger lymph nodes". He still has the large lymph nodes and they are visible on both sides of neck when he turns his head. Is this something to be concerned about?