What Could Recurrent Contractions And Pain In Sternum Indicate?

Hello! I'm a 26 y/o male, 168cm/74kg. I'm having weird contractions in my chest since yesterday. It is hard to describe. It starts from the the right side of my sternum, at the height of the nipples and runs fast up right to my throat. It happens under about 0.2-0.5 sec, then i feel something like a push with a finger (not to strong) right at the top of my sternum in my throat and then i feel urge to cough. Afterwards everything is ok for a few ten minutes. If i lye on my chest then it doesn't happen, if on my back then yes. If i sit then yes, if i stand then almost never. I've tried to check if my heart skips a beat, because it feels like that, but i haven't noticed a real skipping, or extra beat, maybe a very little delay because of the cough. Btw the feeling that runs up to my throat feels like a vessel that contracts and expands very rapidly. I feel like vacuum inside and then everything is ok. The thing is happening when i'm resting too, no stress at all. I've had an ECG test (not stress test) about 3 years ago and the results were normal.

Thank You for the answer in advance!