I can understand your concerns.
Without seeing the swelling and a proper examination, its difficult to say what swelling it is.
If possible try to post a picture of the swelling in this forum.
Only after examination one will know from which structure is the swelling arising, skin/ subcutaneous tissues/ lymph
The size, consistency, ability to transmit light through it, tenderness/ warmth/ mobility/ fixity to underlying structures etc have to be determined.
Based on examination findings, doctor will order for necessary investigations to arrive at a conclusion.
If its from a lymphnode, look for any infections in his scalp/ ears. On treating the infection, he will get okay.
Hope my answer helps you.