I have been suffering from sinus for the past 3 months.
The way to alleviate it:

- Try to rest some time before getting better
- I use nasal wash using marine salt whole grain dissolved in bottled water , I boil it, let it cool for about 25 min, use a syringe on each nose nostril and let the water drip out on the other nostril
- Use vaporizations of eucalypt, pour it on some water and put the flame on low setting, inhale the vapors for at least 15 minutes That should help minor the sinus
- Put some droplets of chamomille down your nostrils also helps too.
- Wear a buff when going cycling.