Thanks for writing to health care magic.
Since he is only 5 months old I suggest you should take him to the doctor at the earliest possible.
This is because if there is any infection which is responsible for this that my turn into sepsis
in that age group. Your son needs to be investigated further for the exact cause of fever
Continue to ask further queries as required.
Hope this helps.
Dr Y V Siva Sankara Murty,