Mumps is a viral infection that often cause swelling of the salivary glands in the cheeks swollen cheeks in children along with fever and so on. Treatment is mainly symptomatic give pain relievers and antipyrectics like paracetamol, ibuprofen for fever and pain; give plenty of fluids keep the child isolated or at home as it is contagious. It may take 1 - 2 weeks for symptoms to fully resolve, it goes on its own