welcome to healthcare forum. the first thing to be done is to record your temperature with a thermometer when you feel hot,to confirm fever.if that really shows high temperature,we need to find out the cause.we have to a full blood count,ESR,and depending on the result,other investigations if needed....common causes of longterm night fever includes chronic infections like typhoid,tuberculosis etc.these are usually associated with a low appetite and fatigue.other less common causes can be connective tissue disorders/hematological disorders.most of them can be sorted out with the above said investigations. i hope you find this information useful.wishing you a faster recovery.thank you.