Weird intense thud feeling in middle of upper left side of chest.... not sure if it is heart issue or not... p?

Ok you basically described me! i'm a few years older though. but this morning i had this large thud like feelings in the same area like right under my left breast. I was just lying in bed when it happened and it happened so suddenly i almost thought my cat jumped on me! Its the first time anything like this has ever happened to me. I also have anxiety really bad, but it doesn't seem to be something related. I've never had any medical problems so this is really scarring me