Paul, I am on week 3 of that same virus! Exactly the symptoms you are talking about. Light plegm, scratchy cough! I have tried high doses of vitamin c, vitamin d, elderberry extract, homeopathic remedies for coughs, multi vitamins. Would get better, then come back.
Since yesterday I am doing the hydrogen peroxide inhalation method every 3 hours and sipping straight apple cider vinegar with a little hot water added. Felt better right away. The straight acv has stopped the cough right away. I just need to remember to keep sipping it. Not so bad if you add hot water.