If your child has been confirmed to be suffering from mono then this illness would correct by itself in a 2-3 weeks.
Only symptomatic management is required like Antipyretics and pain killers with lots of fluids and bed rest
.If the tonsils are painful and swollen she could take warm saline gargles which would relief her of the pain.
The only complication is to do with liver
.Liver swelling leads to jaundice
and swollen spleen could lead to rupture if outdoor sports activity are indulged in .Hence one should avoid any contact sports for a period of 4weeks post infection.