What Causes Spasms And Twitching Chest On The Left Side?

The left side of my chest keeps spasming or twitching alot. This has been happening for several days. I listen to my heart beat with a stethoscope and the heart beat seems normal and seperate from the spasm or twitching. Any insight what his could be. My heart is not racing or anything like that. I have no pain it s just calmost constant twitching or spasm s on left side of chest. You could actually see the chest twitching as it spasms. Any insight would be great.