Hi Doc. Able To Help Give Some Advice. My 2yrs7mths

Hi doc. Able to help give some advice. My 2yrs7mths boy just recover with viral fever for 5 days. Then his body temp sudden drop to 35degree and slowly it went up to 36.5. But this few days i keep monitor his body temp is always kept in 36.3 to 36.6 degree. He is active and had appetite on eating. But during nap n bed time he always had heavy cold sweat. Body is slight cold but his palm n feet is warm. What causes or symptoms is that. Should i be worried?