Hi I Just Felt My Left Peck Muscle Sort Of

Hi I just felt my left peck muscle sort of twitch. I had some weirdness with my heart a few months ago but a cardiologist in the nethlerands says I'm fine. During that incident, my heart started racing when I was just sitting still. and even now when I lay down or get into a certain position and I can feel my heart beating, on occasion. I haven't had angina or anything else. I quit coffee and black tea (though on occasion I have green tea, which I just had before the slight flutter) and I quit alcohol (I have had maybe 5 or 6 drinks since March).