Online suggestions without seeing the patient is not advised for this case.
And thorough investigation is required as history is of 20 days.
During fever baby should be very minimally dressed after giving medicines for relief, even if there is mild shivering.
But fever is a symptom and not a disease, we need to look for the cause of fever and abdominal pain.
If it is urine infection, then antibiotic according to culture needs to be started
Next Steps
Please consult in person for better evaluation and treatment