Feeling heart beat when resting, eases after taking Metroprolol. Should I be concerned?

weigh roughly 390 lbs and I am an active musician (a drummer) I have GERD and I am currently taking Omeprazole (40mg 2x a day) and Metoprolol (50mg). The GERD symptoms seem to have developed over night on my 23rd Birthday 8 months ago, at first I thought it was heart problems which caused me to have a few anxiety attacks , which at first I thought was a heart attack ...which only fueled my anxiety and made my condition worse, this has carried on for months and even though I ve had tests run on my heart (I had an echo cardiogram in May) and I ve been told it s perfectly fine...it hasn t eased my anxiety...and I have a few every day symptoms that keep me on edge and anxious...one is that I can feel my heart beating throughout my body when I m sitting/laying down at rest and it feels like it s beating pretty hard (hard enough to make an object on laying on my stomach shake with it) and gets worse when I get up from a sitting position or do even the slightest of adjustments and this goes on throughout the day but gets a little less obvious after I ve taken my Metroprolol. Is that something I should be concerned about? Another is, it feels like my heart stops beating when I take a deep breath, then starts again with one hard beat when I let my breath go, is that normal? Also, my breast plate makes a popping sensation when I stretch during a GERD flare up, I ve heard that is caused by irritation in that area but I couldn t get my doctor to confirm this for me...honestly I couldn t get her to confirm or clarify many of these issues for me...Anyway thank you for your time, it is greatly appreciated.