I think I breathe through both nose and mouth. But I have a slightly different (and very irritating) problem: On at least one of my runs each week, my ears start to feel blocked, especially my left ear. I'm left shaking my head like a dog (which must look weird to passers-by), but effectively my ears don't feel very pleasant, and I can't seem to shake it. And no, swallowing doesn't help either. Any ideas?