Welcome to healthcare magic forum..
I am sorry to hear about your baby..There may be various reasons for prolonged fever
such as Bacterial disease such as abscess, tuberculosis
, UTIs, hepatobiliary infections, Viral diseases such as HIV, AIDS, Fungal infections, Parasitic infections, Neoplasms such as lymphomas, leukemia
vascular diseases,Endocrine disorders etc. Your baby needs a detailed investigation including all the blood investigations, Xrays and CT scan to determine the cause of prolonged fever. I would suggest you to consult a paediatrician especially when your baby has an episode of fever and get these investigations done..
Hope this helps!!