Hello. I Am A 66 Year Old African-American Woman. I

Hello. I am a 66 year old African-American woman. I take lisonpril and metoprolol for high blood pressure. I was taking 2 - 50mg of the metoprolol daily - one in the morning and one in the evening. My doctor change it to 1 -100mg to be taken at bedtime because I was feeling fatigued and he said that medication would that affect. Last week, I started noticing a "vibration" in my left chest area. It is not consistent nor is it painful. It started again today about 30 minutes ago and it didn't happen at all yesterday. Could it be due to stress or is it heart related? My email address is: YYYY@YYYY