temp help

So I had a temp this morning of 96.9. It's fluctuated between 96.9 and 97.1. Just started temping too. My thermometer broke so I had to go buy a new one. When I got home I tested it out making sure it worked good. My temp was 96.63. How after walking around even outside while it's 86 degrees am I lower than when I first woke up?