Hello, I've Been Feeling My Heart Is Going Faster Than

Hello, I've been feeling my heart is going faster than usual mainly when I wake up, this morning I checked my hear rate and it was 171, it got normal within a couple of minutes and this afternoon while at work it was 114, again it got normal a few minutes after.
I've been feeling very tired and even tough I work 60 hours a week and that could be, I feel like it is way more tired than I should be because I'm 24. I've also been feeling fainting sometimes, like I'm at work and all of a sudden I wake up and realize I'm there