Hello, so for about 2 months now I have been noticing that when I lay down to rest my heart will start beating really hard and when this happens I also get shortness of breath. I've never had this problem before but I do know that when i was born there was a murmer that the doctors were worried about but then I guess ended up being fine with my doctor. I dont know if this has anything to do with what I'm going through or not but I'm starting to worry...please tell me its not serious!