You are sick already.
I haven’t read all of the above, but if youw ant to not get sick next time there are some things to know in general:
DON“T TOUCH YOUR FACE. I was told this throughout my childhood, and it seems this chant has gone away. We get sick by touching something and then putting the germ into our eyes, nose, or mouth. We cannot wash our hands every 5 seconds, so if you never get that germ from your hand to your face, you probably aren’t going to catch a cold or flu, unless they are coughing and sneezing on top of you. A good habit is to use the back of your wrist if you have an itch or something and not use the inside of your palm or fingers if you need to touch, because you use the inside of your hand to grab door knobs and if you shake hands they are not touching that area.
Generally people are most contagious 24 hours before and the first two days into the symptoms of the illness (depending on what illness it is), so if someone is just starting to feel under the weather keep away from them.
Check your overall health, for women low iron is big, But for both sexes many people are difficient in vitamin D and B12. I don’t think you can get rid of a cold once you have one by taking bunches of vitamins. The vitamin C study had never been able to be duplicated and pretty much is not considered valid.