I was diagnosed by my primary care physician with anxiety disorder a few months ago and I've been on Lexapro for about a month and a half. I thought that shortness of breath was caused by the anxiety, and the Lexapro seemed to work immediately. Now, I don't panic, but I have episodes of shortness of breath for no rhyme or reason throughout the day. It just feels like I can't take a deep enough breath for several minutes. I also have cramp-like pains under my rib cage, especially on my left ribcage and sometimes up closer to my collarbone. It is hard to attribute to just anxiety, but everything appears to be fine with my heart and lungs.