When it finally stopped raining out here my sinuses flared up. I figured, okay, the rain stopped, sun's out, something bloomed, no big deal.
Days - days! - later I finally figured out that it was an honest to Bob cold. I haven't had a cold in years.
All the old remedies do help, though I'm not drinking vinegar for any reason short of the end of the world. For an alternate astringent I find that blueberry juice helps clear my throat, though if yours if raw it might sting a bit. The night cough is mostly positional, as you've noticed; propping yourself up does help a bit.
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In a time of universal deceit, telling the truth is a revolutionary act.