My son age 2.5 years , weight 11.8kg , from last night he has fever , temperature frequently changed between 99 to 100, some times 100.6 , but there is no change in his behavior, he is playing as regular day ,we we have given t-98 syp 5ml when temp arise 100.6, temp drops for some time ,then again flactuting between 99to 100, there is no sign of cold or cough or any other , what to do??