Does it just pound or does it feel irregular and fast? If irregular and fast you could have a arrhythmia
such as premature ventricular contractions which is common among all of us. However, it is deadly if it lasts too long. But it does cause those type of symptoms.
And ECG or better yet, a holter monitor
that monitors the heart rhythm for 24 hours will help determine if you have an irregular heart beat.
Also, after you eat, a majority of you blood flow goes into digestion. Make sure you get plenty of fluids, unless you of course are directed not too by your doctor.
But you should see a doctor about this immediately.
It also could be something you are eating like caffeinated products (soda's excess sugar and so forth) that can cause fast heartbeats, and make it feel as though your heart is beating through your chest.
Unfortunately, there is no way to determine your problem without going to see a physician and having the proper diagnostic testing.
Remember you only have one heart.
And the reason so many athletes die suddenly on the basketball court or other places is due to PVC's as stated above, but when they are prolonged, it's called ventricular tacchycardia...and deadly.
Healthy has nothing to do with it.
One heart....one life....go see you doctor today!!
Hope that helps!