Hi i am a 20 year old healthy female with a normal bmi, pulse and blood pressure. Recently i started experiencing this weird sinking feeling in my upper chest near my throat that last only a 2 Or 3 seconds. It's painless but i feel like my heart stopped and started again during that time. It's a the kind of feeling that we get in our stomach when on a roller coster. I have had mant tests such as a blood tests, ekg, and chest xray done. All came out perfectly fine. It's really disturbing and scares the hell out of me can anyone tell me what it is and is it dangerous? Thank you