If I feel like that, I take a mega dose of vitamin C, like maybe 2-3 grams, then a gram every few hours. With a sore throat, I would spray some ehinacea/propolis throat spray by Herb Pharm in my throat, and/or gargle with warm salt water. I would make a hot drink with honey, lemon, crushed garlic and ginger, and a dash of cayenne, and drink it as hot as I could stand it. I would also crush some garlic on a spoon, cover with raw honey, and swallow it whole. Depending on what I had time to do. If I was still trying to do everything and had a busy day, and didn't really feel that bad, my biggest prevention things are vitamin C, and possibly a thymic protein supplement, and maybe the garlic.
Hope you feel better!