Any ideas on what this health affliction might be (see details)?

I know Fluther isn’t the place to get medical advice; I’ll see a doctor of course, but no one has ever been able to diagnose me before. I’m just looking for suggestions.

I think I’m starting to get a respiratory infection that I’ve had twice before but that has never been diagnosed. I’ve gotten it once per year the past three years, but it doesn’t happen at a particular time of year. For a week or two before I get any severe symptoms, I feel short of breath and like my lungs aren’t filling all the way, which gives me the urge to yawn a lot. Then I’ll wake up one morning with sharp chest pain (it feels like it’s from my lungs) that radiates into my shoulder. Chest x-rays have never shown anything. No cough. Lying down makes the pain a lot worse. I can’t draw in deep breaths without extreme pain. Doctors have guessed at pleurisy but it’s odd that I never have a cough or any visible inflammation. I had thought that it was a side effect from a heavy-duty med that I used to take (it has high risk of respiratory infection) but I have been off that med for seven months now, so I’m quite distressed to be finding out that this is something I’m still going to have to deal with…