Hello @Kristenstrack and welcome to the Community. You are describing a device problem. What model Fitbit do you use? Some independent reviewers have left reviews on their sites that mention irregular heart rate tracking. Also Fitbit recommends wearing your Fitbit farther away from the bony part of your wrist while exercising. That might help.
Laurie | Maryland
Sense 2, Luxe, Aria 2 | iOS | Mac OS
Take a look at the Fitbit help site for further assistance and information.
Best AnswerMoved fitbit up my wrist and did not fix the problem.