I'v scanned through the above, but not read every word. I did not see anyone mentioning SLIPPERY ELM, an old-fashioned herbal remedy that works very nicely as a throat lubricant. Available in tablet/lozenge form at health food stores, under the brand name "Thayer's" (and perhaps other brands as well).

Won't cure an infection, of course, but alleviates the symptoms and allows you to speak and sing comfortably.