Enlargement of mesenteric lymphnodes in children can be due to many reasons like Viral infection,Appendicitis
If the child is not having severe pain
,he can continue with Antibiotics and antispasmodic like Dicyclomine
Mesenteric lymphnodes will take time to subside .
If your child has severe pain ,then you should consult a Surgeon and go for Appendicectomy.
As per literature(Bailey and Love textbook of Surgery),most of the children will be relieved of pain in Mesenteric lymphadenitis
after Appendicectomy operation.
So,proceed according to the pain of your child.
Wish him good health.