Thank you for your query.
It is unlikely he has tuberculosis
if he is not symptomatic ie he has fever,weight loss/failure to thrive
,history of contact or histologically proven lymph nodes.
Usually BCG is given on the left arm.It can provoke lymphadenopathy
at that site.Mantoux/tuberculin test if done below six months it can give a positive reaction due to the BCG vaccination
A FNAC or excision biopsy
of the gland is the gold standard for diagnosis.
If the child is clinically OK...it is prudent to follow up the child rather than start anti tubercular drugs.
Consult your doctor if the problem persists.
If you have any further queries you are free to consult me.
Hope this answers your query.
Wishing a speedy recovery.
Have a nice day.