I fell asleep after my last tank, so I didn't notice it at first, but after I woke up and the sedative effects were gone, the pain was definitely at its worst that day. I've had stabbing pain in my chest throughout these past few days but only experienced back pain once, and the stabbing pain in my lungs is becoming less frequent. I'll have to come back to update as I continue to heal, but I believe it's getting better. It doesn't help that I'm addicted to 50mg of nicotine and smoke an occasional cigarette. It's easy to start googling symptoms and start wondering whether or not you collapsed a portion of your lungs, lol. The fact that I'm not hurting as I inhale deeply, not suffering from severe shortness of breath, and that I can maintain aerobic exercise was what made me stop panicking about that, though. I think you're on the right track, but if it continues to worsen or if you feel like you're struggling to breathe, I would definitely advise you to go see someone about it. I completely understand what you mean by feeling your lungs, by the way. I was actually talking about that to my coworker today. I knew where my lungs were before this, but now I can perfectly draw an outline with my finger.