3yr old temp went from 99 to 96 in a couple hours..how low.is dangerous? its freaking me out! :'( she has not had any kind of fever reducer

Low temperature: A low temperature can be a sign of illness just as a high temperature can. If she is otherwise sick, have her examined. I am not sure what kind of thermometer you are using and if you may be experiencing trouble with accuracy. The gold standard for temperature is a rectal temperature until she is able to keep a thermometer in her mouth. I hope she is well. All the best.