Toddlers get fevers often from teething or a virus that they came in contact with from other children. High fevers improve with alternating ibuprophin and tylenol; ask your pediatrician first.
If a child has a fever you should rotate tylenole and motrin every two hours. The dosage should be determined by their weight instead of age and you should consult with your pediatrician.
Dehydration could be causing your toddler to have recurrent fevers. If a fever is present, you must check it frequently to determine whether it is increasing or decreasing.