This happened to me once, i was laying on my arm/elbow looking up at the tv when it happened. Sinus mucus clogged my airway, it was scary i got up really quick. I don't remember how it unclogged it happened so fast maybe gravity & sucking got it unclogged. Felt as described, my shihtzu(RIP) always had it. Im guess from all the dirt & dust irritating their nose making them get mucus/acute allergies.