i recommend getting it checked out. sometimes getting a second doctor's (or even third's) opinion is great! i had a health issue and i went to multiple doctors before any of them figured it out. you know your body best and you know when something needs to be figured out!
during exercise my heart will go into hyperdrive then skip several beats in a row i can count to 5 before it restarts. this has happened to me a few times over the years. typically i am exercising and my heart rate will increase very rapidly for a few moments. suddenly it will stop pounding and i cannot feel my pulse and my hr monitor shows 0 for a few seconds. i will get dizzy and sit down but then it starts up again like normal. i am 28 healthy and fit with no history of any health issues. i have mentioned it to my doctor but she just said "huh thats weird" and said to get it checked if it happens more.