Hello,I have a peculiar symptom which feels like a short blast of squeezing pain (like cramp) behind breastbone. It lasts for less than one second but it is quite alarming. It can happen during stress, but it can also happen without any obvious cause. After this "alarming" second, it is like nothing ever happened. Could this symptom be caused by a heart disorder? I am 25, male and otherwise healthy.Thank you.