I studied medicine but only practiced for two years and left it and got into business. There are some thing that will help but the flu is just a wait and let the body take the virus on.
For the sore throat gargle with one part water with one part apple cider vinegar. The vinegar will kill the virus in the throat, also some use salt with water but the salt need to be the one that has iodine in it. Another one is gargle with peroxide with water.
For the sinus use salt with water and use a dropper and drop in the nose this may help some.
As a perpper you need to save aspirin, ibuprofen.
Also save some zinc and start taking the minute you feel you are coming up with something.
I drink a lot of green tea with honey, hot.