Suggest Medication For Urinary Infection

sir, my 14 year old daughter underwent an laparoscopic operattion for the cyst formation in one of her ovary after that she was doing fine but during the past one month she developed cold shivering for which the doctors diagonise was urine infection now she gets cold shivering almost all the days and doctors have given heavy anti biotic but she continiue to be in the cold shivering please answer