I've been dealing with shortness of breath for about 10 days now. It gets worse when I'm working or even when I'm resting. It's kind of annoying because this has been happening on and off every few months. I went to a chest physician and he said everything seems fine after doing a spirometry test and a chest x-ray, which were both normal. I'm confused and a bit worried because I still feel breathless. Could there be something else going on that's causing this problem?