Whatever you do, please DO NOT slosh anything around your nose and sinuses as you run the risk of introducing infection which can be very difficult to get rid of and can, in rare cases, eventually cause meningitis or a particularly evil problem called Lateral Sinus Thrombosis. If you are under the care of a doctor for ANY condition please do not try, or use any form of Folk Remedy without consulting him or her first.
It may be a good idea to ask your GP to do your IgE levels for Dustmite which can cause chronic inflammation of the nasal mucosa.