For years I have had this problem, it feels like my left lung is being pinched by my ribs, I can't breathe; I have to take short shallow breaths. But if I take a really deep breath, its excruciating pain, but then it just pops and then I feel nothing. No pain what so ever, like it never happened. It’s very random. It will hit at any time; I will get it once a day for a week and then go months before it happens again. Last time it happened was during intercourse a little over a month ago, but the time before that, I was sitting down watching TV. I asked a doctor about it when I was younger and they shrugged it off, so I didn't think much of it. But now that I’m getting older, I’m getting worried that it may really be something. Any ideas? I will definitely be asking my doctor next time I go in.