Gosh, you are IN the hospital? That's good...but not good...if you get me. They'll do tests and find out if you have any clots, blockages, heart damage (D-Dimer enzyme in your blood shows if clots are dissolving, images will show blockages, and heart damage is signified by troponin, also in the blood, all of which they will do). Also, a 12 lead ECG will show if there is anything odd with your heart's rhythm. You're surely in excellent hands.
To answer your question, I was near the end of a 10 km run (65 at the time, a lifelong runner) when I felt my legs suddenly weaken and slow like they had excess lactic acid...if you are familiar with that sensation. I sat on the curb, took my pulse, it was rapid, but kept on after a few minutes. After cooldown, showering, at my compute, my heart rate felt fast through my chest wall. Went to the ER, they diagnosed paroxysmal atrial fibrillation. So, some weakness, some minor breathlessness at times, anxiety, feeling unwell, and the thumping and bumping in my left chest wall.

Thats not a bad Idea if your close to a Mayo Clinic and you're having symptoms go to the ER. The breathing issue sounds just like it could be fluid around the lungs. I always thought fluid could build up in your lungs which is Pneumonia. But around the heart is when the sac around the heart and lungs i had never heard of until it happens to me and it will give you a breathing type symptom.
But any good ER should be able to help figure it out. Particularly if you're having breathing problems.