Hi, I`m 51 year old female a little overweight , good blood pressure , no other health problems, but I have been having some irregular heartbeats even when I`m resting. I also feel pain with every heartbeat when I lie down or when walk from one room to another and then sit down. I have been to the doctor severl times and have had stress test, echo test, blood test and doctors say my heart is okay...what could this be??