I've had 2 different kinds of "bubble." One I KNOW was from anxiety and it seemed every breath was a huge labor...akin to a "broken heart" feeling of love lost from my early youth
But the other time was an honest to god BUBBLE that hurt like all get out and persisted for several days (3 hours in an ER) making the pain of a full breath almost unbearable....hence half gasps. All of a sudden at day 3 it went BLURP and was gone as mysteriously as it had popped up.
MD's conjhectured I had gotten a glob of water into a lung and since it started while swimming, that seemed reasonable to me. Since I was in my 20's at the time, they didn't seem concerned about my heart. It never happened again.