What Causes Shortness Of Breath Along With Palpitations Of Heart?

ive been having random shortlness of breath and my heart feels like its skipping beat at he same time, but ive checked my pulse and its normal but it feels like my lung is collapsing. its only happening in my left lung right right lung seems to be finel. this has been happening all day long now and i dont want to go to the hospital as i have to work in the morning, and i have previously been to the hospital 3 times with the same symptoms at this hour and have been told that im fine and been sent home