Irregular inter-cardiac cycle periods. What's wrong?

Heart health and blood vessels
1

During exertion my heartbeat tends to go:

lub-dub (short pause) lub-dub (long pause) lub-dub....

It is definitely irregular, and I am positive I am timing/counting cycles, not systoles/diastoles. What could be wrong?

I am 15, very fit (if I may say so myself), I eat healthy, but the past two weeks I have been eating less, cutting for summer. More elaborately, for if it helps:

Breakfast: 55g of oatmeal with milk, fruits, medium portion of baked tomato beans. (440 kcal)

No lunch

Snack: 1 quesadilla, fruits/veggies, 1 or 2 plain rice crackers (260 kcal)

 

Dinner: Very large portion of rice with chili con carne, fruits/veggies. (750 kcal)

It adds up to about 1440 calories, but before you assume an eating disorder, note that I had little to no exertion that day. All I did was bike moderately to the gym (3.5 km) do a really underwhelming workout, and bike back.

So in short: 15 yrs, fit, male, 1440 kcal.  

2

Do you drink energy drinks?  Like Monster, Red Bull, Amp, 247, 5-Hour Energy, Mountain Dew, or anything in this category?  If drank in excess these drinks are known to cause heart palpitations, and worst of all, heart attacks and death. If you don't drink energy drinks I would suggest seeing a doctor or going an ER ASAP.   

3

I don't think skipping lunch is a good idea and you diet seems a bit low on protein for someone of your age.

I think the skipped beats do need looking at to rule out atrial fibrillation which can affect people of all ages so an appointment with a doctor (or nurse) would be appropriate - they can give you a rough idea by just counting your pulse for 1 minute to detect the skipping and then would recommend further action if needed.

Take care and maybe up the protein (eggs, meat, fish)!