What Causes Popping Sound In Ribcage While On Exertion?

Hello, I have this weird/strange sensation. Below my rib cage, on the left side (like 1 1/2 inch) from xphoid process, if I press in or am doing some kind of physical activity I feel a popping sensation. Also I can feel it pop in and out when I am laying flat on my back, just breathing in and out. It usually doesnt cause any pain but some movements hurt more. I had this for about a year now after a really bad virus where I was coughing all the time. Any idea what could it be?