Hi and thanks for the query,
the pain associated with fever
could suggest the presence of a septic arthritis
. It is important to exclude septic arthritis for its a medical emergency. An x ray
of the ankle shall be very important to be done. A full blood count shall be important in search of raised white blood cells is very important to be done. Searching for markers of inflammation are fundamental in the management. This shall also be important in excluding other causes of fever. Consulting your general practitioner is my advice.