We have a Neti pot in our household in case of cold/congestion. Once you get over the eww factor and the fact it feels weird to do, it does work very nice.
My 9-year-old daughter used Nasonex last summer due to the fact she has a grass pollen allergy; she never had any problems/symptoms like you're describing. She also used an irrigation sinus cleaner too, though, so not sure if perhaps you need to irrigate your sinuses as well as using the Nasonex.
I also wanted to mention that more allopathic doctors are unaware that an allergy to casein or whey proteins, which was found in cow/dairy products, can produce sinus/sinusitis/rhinitis problems.
I suffered from sinus problems and congestion for years--in fact, I even had to have a permanent T-tube put in my right ear after sinus problems made my eustachion tube collapse--and when a naturopathic doctor tested me and it was discovered that I have a severe casein allergy--wow! what a difference it makes when you give up eating/drinking something that makes you feel sick!
I have been off all dairy now for two years and have the best and uncongested sinuses I've ever had. I also have no bronchitis, and my asthma is clearing up as well! My asthma specialist is absolutely dumbfounded that giving up cow dairy could have such an impact on my health. He is cautiously saying that dairy "could" be a promoting cause--remember, allopathic doctors are not taught to look for the cause of the problem, only to put a Band-aid on the problem. So for him to even acknowledge that cow dairy might be a contributing factor in my rhinitis/sinusitis/asthma problems is a very big leap.
And a real bonus for me, because he's willing to work with me on it. I've gone from taking Advair 2x/day to only once, and it's looking like my asthma only flairs in cold weather, so I should be able to get off it in the summer. And if I continue to work with my naturopathic doctor and get my body back to what it should be--healthy--I might be able to get off Advair completely.
Sweet.