Hi ...did you measure temperature in mouth or axilla ? Presuming that you took in axilla , temperature from 96.9 to 99.2 to is normal ...the thermometer must be kept at  3 min  under arm or 1 min in the mouth , then only it shows correct  reading ... also digital thermometers are many times  inaccurate...sometimes sweat in axilla or clothes coming in between cause low reading ... Generally low temperature  does  not occur in previously normal healthy children that easily ...most commonly it is due to wrong temperature measurement..