Thank you for your query on Healthcare Magic.
Pain abdomen with enlarged mesenteric lymph
nodes is a relatively common problem in children and eve after with extensive investigations the cause for it is unclear.
Some times non specific infections of the gut like viral may cause increase in size due to inflammation and pain.
In such type of infections just symptomatic treatment with dicyclomine
in prescribed dose is required and child should be in regular follow up with ultrasound
abdomen to look for any increase in the size and for further evaluation if required.
Hope I have answered your query.