How does 1 year old baby still have a fever to do diarrhoea

One year old baby has fever with diarrhea symptoms, most likely caused by gastrointestinal flu, and his diet is not clean, eating cold food has something to do with it. To relieve the symptoms of fever and diarrhea, should be treated with antibiotics for gastrointestinal bacterial infections. If there is a high fever, should be treated with ibuprofen and other drugs to reduce fever.