OK. This is the bottom line.
There is no cure for the common cold. Best way to deal with it is to stay home, rest, keep hydrated and subscribe to some service that will allow you to view all the boob scenes in Game of Thrones.
All of the "cures" are weak efforts to mask the symptoms. Some work better than others, but why mask it when all you need to do is rest and recover. This is what sick days were designed for. My apologies to the self employed.
Oh, and best sinus clogging fix is a mix of vics vapour rub (or, more accurately, eucalyptus oil) and lots of chilli in soup. That will blow your tubes out, but will not cure anything. Again, time resting is the only cure.
Flu is short for influenza and is a name covering thousands (literally) of viruses, most of which mutate to other variations over the years. That's why there is a different flu shot each year. The shot is made up to cover a small number of flu viruses that they calculate will be common over that particular year. The shot sensitises your immune system so that when the nasties turn up on numbers, it's pre-primed for the suckers. So if a new virus turns up, you can still get the flu even after having the shot and it won't work if you take it after you get the flu.
Antibiotics are for bacteria, not viruses. Taking antibiotics will do nothing to cure flu.
When you get the flu, you will feel like you have been punched in the kidneys by Mike Tyson, after he has raped you. And not in a nice way, like the innocent frolicking fun of Brock Turner (I wonder if the sentence would have been different if he was black). When you get a cold, you just feel like crap and have your immune system flood your sinuses with mucous to flush out the bacteria. People call the cold a flu, but believe me they never confuse a flu with the common cold. Different animals. Kind of like a mouse vs a gorilla.
So. Stay home, rest, drink lots of liquids. Same for the flu, only it takes much longer. Dats it.