What exactly is wrong with the child who suddenly has a high fever?

Patient's question:

Medical Description of Child's Condition: My child is two years old this year. Three days ago, our child suddenly had a high fever, reaching up to 40 degrees Celsius. We took them to the hospital for a check-up, including blood tests. The results indicated a bacterial tonsillitis (as the doctor said). However, the doctor also examined the throat and noted that there was no redness or swelling yet. The symptoms started to appear after a couple of days! Later, our child received intravenous fluids for three days, but there was still no improvement. Over the past few days, they have been feverish on and off. The fluids administered were Ceftriaxone and Influnixin. Today, I noticed that our child can no longer walk properly, and it causes them great pain to stand straight. Even when they manage to walk a few steps, they move with a large belly, inching forward slowly. However, sitting, lying down, or turning over does not cause any symptoms. What could be wrong? Personally, I think it might be possible that our child accidentally injured their waist, causing the high fever. Is that

Doctor's answer:

Hello, fever can be caused by bacteria, viruses, or colds, among other things. The process of fever is also the body's fight against viruses and bacteria, which can be beneficial to health. However, if the temperature exceeds 38.5°C, it may lead to febrile seizures in children. You can use lukewarm water to bathe the child. If you have ibuprofen or acetaminophen at home, it is safe to use. Wait until morning to go to the hospital for a check-up, including a blood test to determine whether it is a viral or bacterial infection, and then consider medication.
To prevent febrile seizures in children, parents should ensure the child drinks plenty of fluids, monitor their temperature regularly to avoid fever, and pay attention to dietary nutrition. During flu season, it is best to minimize outings.
It is recommended to give the child plenty of fluids and administer antibiotics or antiviral medications based on blood test results. A lukewarm bath or alcohol rub can also help lower the temperature. If the temperature exceeds 38.5°C, fever-reducing medication can be given, but not more than four times a day.