I woke up and my heart was beating really fast.

I have had problems where my heart feels like it goes fast for like two beats and then it goes normal. About once every couple of months my heart will race like 170 for about 5-15 minutes. Not sure what really triggers it because I have had it happen after exercise and woke up from it doing this also. I have had a MRI and they found nothing. They done an ultrasound of the heart and found nothing. They also done ECG of the brain and found nothing. The other problem I have is when I exercise like when I bike or go upstairs I get short of breath to the point I have a hard time talking. Plain old going for walks don t bother me at all. I also get on and off spells of my face and arm and fingers feeling numb and tingly. Any ideas what this could be? I am just so frustrated because they can t find what is wrong. I am just to the point I will just deal with it and ignore it when it happens. I just hate it because they cant find anything with those test above and I know what is happening is not normal. But I am to the point I will call it normal for me!

i woke up to a loud heart beat two weeks ago. also some nights while falling asleep, i feel like my heart stops for like 3 seconds and sometimes beats slow too. i am 44years old. 100 pounds. eat healthy and exercise 3 times a week. i also have been feeling few heart murmurs . i can t tell if it is a murmur or acid reflux as well.