If that's measuring in fahrenheit, you should be dead, so let's assume the thermometer isn't working right.
What kind of thermometer is it? If it's digital, it's likely the battery is starting to die. Do you have a food thermometer in the kitchen? You could probably test your odd thermometer by first measuring the temperature of something (warmed up food or whatever) with your kitchen thermometer then use your body thermometer and compare.
It's not impossible for your base body temp to be the same a few days in a row if all the conditions (wake-up time, how well you slept, how warm it is in the room) are close to the same. Most of the literature I've gone through about charting body temps recommend using a mercury thermometer for greater accuracy.