It's really every now and then and it has been so for more than 6 months already I guess but, every several days i'll feel a weird sensation. It suddenly feels as if my chest was lightly pressed, then noticing it may have been a hearbeat (or not) followed by 2 or 3 really strong heartbeats (I'm sure these ones are indeed heartbeats) they're strong, making my chest feel weird (not painful but unusual and kind of like a push) and then it just goes back to normal.

I'm almost 18, could this be a really serious problem, a significant problem, a not so important one or should i just ignore it?