Your Pinterest analytics fluctuate on a daily basis depending on how many people viewed your pins or engaged with them. This can change drastically between weekdays and weekends and if a pin is going viral vs when it’s not. What is more important is to look into your Google Analytics or store analytics and double check the numbers.
If you see drastic changes in your pin analytics, don’t be surprised as sometimes when Pinterest makes feature updates analytics can go up and down. The best place to figure out if something is really wrong with your account is to email Pinterest support. You can send an appeal asking them for more info under “Measurement & Analytics.”