does anyone get the horrible feeling where it is adrenalin - but feels like it could be something else (even though it is adrenalin) and just completely rushes all over your body.. it lasts for a very short time. it scares me so much and always makes me run or walk fast in a direction to nowhere, and i cant help but feel like im going to die everytime this occurs, it starts with a slow heart rate and then my heart begins to pound after. is this natural?