as your child has few lumps in the neck,he should be examined throughly for any infection.
In medical word it is called lymphadenitis
,it may be acute or chronic.
If a child has infection in the ear,nose,throat or infection on head or scalp like boiles,dandruff
,can cause enlargement of lymphnodes
But commonest cause is of tb lymphadenitis.
Do blood test
for ESR,Montoux test.
consult your pediatrician
and seek his advice