I've been feeling a bit breathless since April 13th. It eased up a bit, but then from April 18th, I started getting out of breath even when I'm just resting. I don't have any chest pains or a constant cough, although my cough sometimes sounds deep, and there's a wheezing sound when I take a deep breath. I haven't had any fever or chills either. It's been over a month now, and this breathlessness just isn't going away. What could be causing this, and should I be worried?