Thanks for writing to us.
He can either see a surgeon or dermatologist
to get the lesion dignosed and treated.
from the description it could either be an abscess
or an infected sebaceous cyst. Both are easily treatable. An abscess would require incision and drainage
of lesion with oral antibiotics
while sebaceous cyst would require oral antibiotics initially and when the infection subsides, the cyst needs to be excised completely. Please see a doctor nearby.