### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
I had a lot of test done to find why my heart beats crazy fast all of the sudden...sometimes I am laying in bed quite, sometimes I am pretty stressed, and sometimes when I hiccup..... it races for sometimes 5 or ten minutes...never more than that....sometimes laying down or inverting stops it. always get a head rush when it stops, I am a little shakey ....then after for couple minutes then I feel fine. doctor told me my heart is great....it may have been the sudaphed and zantact I took with in a couple minutes of each other.....I have had this for many years.....I drink one cup of coffee every morning(1 a day only) 30 years ago used to drink 10 a day. I am 56....5-10 1/2 tall...180lbs.....work out regularly. Also seemed that a few years back I would have these a lot....found out that crystal light caused it.....with further investigation it was aspartame? I think(sweetner) in it...is that possible? I only have I an attack every once in a while ....instead of almost everyday when drinking crystal light. any thoughts? Thank you.

### output:

DearWelcome to ChatDoctorWe understand your concerns went through your details. You should understand, worrying about something more and more worsens our thinking about the scenario, and we worry more. That is called obsession. It becomes more so in the case of health related problems. You feel your heart rate because you are obsessing with it. That is natural. Your doctor has given your heart a clean chit. Your heart races whenever you are anxious or feared. Stop being anxious about your heart because your doctor is sure about that. If you still need my assistance in this regard, please use this link. http://goo.gl/aYW2pR. Please remember to describe the whole problem with full detail. Hope this answers your query. Available for further clarifications. Good luck.