Maybe due to sweating..give plenty of fluids. Fever can cause fluid loss and dehydration, so drink water, juices or broth. For a child of age 2, use an oral rehydration solution. These solutions contain water and salts proportioned to replenish fluids and electrolytes. Rest. Baby need rest to recover, and activity can raise  body temperature. Stay cool. Dress in light clothing, keep the room temperature cool and sleep with only a sheet or light blanket...consult pediatrician for further help Regards