Hi, welcome to healthcare magic, I am sorry that you feel unwell
Treatment of flu
would involve rest, copious fluids, paracetamol
to help with the joint aches,sinus pain and fever
, decongestants and antihistamines may help with the sinus congestions.If the viral sinus infection
is complicated by a bacteria, you may require antibiotics.
Since the symptoms have continued for so long , you may want to consider visiting your doctor for an assessment because they are other conditions that may also have flu like symptoms
I hope this helps and you feel better soon