I know this sounds ridiculous of after almost 8 months of hearing my heartbeat and nothing really bad happening well but I am today ..I remember when i was at the doctors office and they brought up that I had a murmur .I had never known that i had one but well it scared me..The doctor said it was nothing to worry about..Yesterday I got out and stayed out most of the day and went from high altitude to low altitude to higher altitude and was there for over a few hours..I was proud of myself doing all the things we used to do. .Last night I tried to sleep but ached all over and today with not enough sleep im not feeling well.I can hear my heart pounding in my head yet everyone that I know professional thinks im listening for it..IM not and hate the sound of it but yet today I started worrying that the murmur may have created the sound and maybe thats what im hearing on days like this ,plus i have had a headache all day and the weather is cloudy but sunny .. just odd.perhaps its my sinuses amplifying the sound in my head but whatever is causing it I wish I would go away ..Im so scared that its some type of problem yet two doctors told me months ago it wasnt and a nurse friend also insist that its nothing but anxiety.l thought when you got out and kept going you were suppose to start feeling better..I don't i feel really bad today and my worries about my heart thundering in my head have started all over again ,although i have no other symptoms of heart disease and my breathing feels ok..the pulse rate seems normal yet my heart finds odd times to skip..It woke me from a sound sleep last night what little I had..and Im hearing it today thundering in my head as scared as I was the first few months I had it..If indeed it was something bad wouldnt i have shown some other symptoms or had something happen to me by now this is been going on for months.. I am worried and scared and hate feeling this way again..Please tell me that maybe its just my anxiety or could I really have heart issues and nobody knows.. and they just think im being a hypocondriac..its really scarry ..what should i do?