when I am in be at night, after laying down for a while, when i breathe in, I hear bubbles..when breathing out, I hear popping. A doctor cannot hear the bubble because it happens when in bed at night. doctors have tried to hear the bubbles during a doctor s office visit. It worries me, but no one can seem to answer what is happening. My lung was checked. O.K. Is it my esophagus? what type of doctor should I see.