It would be better if you could mention the exact position, size, shape of the swelling.
However, doctor has examined your child and diagnosed it to be a swollen lymph node.
Lymph node enlargement in neck is very common in children. Most cases, this happens due to some infection (viral or bacterial) in throat. The swelling may increase or decrease in size over time according to severity of infection.Lymph node enlargement due to cancer (Lymphoma
) is also possible but in that case usually more nodes are involved.
You should visit his doctor again and get him examined. More investigations like USG of the swelling, Biopsy
of the Lymph node, blood investigations may be required to confirm the diagnosis.