How long do sinus headaches last?!
Question: ^?
Answers: ^?
Until you do something about it.
Try steam inhalations.
Find out if you have any allergies or food intolerances.
Take lemon and honey drinks with 1 gram paracetamol. Brandy optional.
Go for a swim in the ocean if possible.
Use garlic and onions in your cooking and other foods that promote healthy mucous membranes.
Try omega three fish oils.
Work out who is 'getting up your nose' and do something about it.
See your doctor if it's bacterial and get some antibiotics if it hasn't gone away by now.
In the mean time try not to stand to close to people on packed buses and trains for your sake as well as theirs.