I agree that using a neti pot for washing out the sinuses, and a nasal spray can help a lot. It was not until I started doing those things religiously, that I had at least some relief from the chronic sinusitus. I am still battling it even after surgery, but I could function more normally after using the wash and nasal sprays.
i can relate - spent years choking on mucous - couln't sleep properly without waking up choking for breathe - and spitting mucous. Horrible. My problem turned out to be food sensitivites. These give me EXCESS mucous: gluten/wheat, soy, dairy, melon, banana, tomatoe. Since cutting out the wheat I made hugh progress at getting back to normal - then the other things became more obvious. Hope this helps.
Prednisone, which I understand gives you side effects, is much more likely to provide relief than methotrexate. It is possible you will find relief in a few days. However it is also possible that you may never have relief with methotrexate. A CT scan of the sinus will show if chronic inflammation is a problem for you.
Another source of your extreme over active sinus drainage could be postnasal drip. This is drainage from the nose and sinuses dripping down the back of the throat. This would explain you choking. After having a virus it is possible for inflammation to linger in your nose and sinuses causing excessive mucus production. A nasal wash helps remove mucus from your nose and sinuses. It is most helpful when done daily before using any nasal spray. A prescription nasal steroid spray decreases mucus production by decreasing the inflammation of the nose and sinuses. This may prevent the postnasal drip. A nasal steroid spray does not provide immediate relief of symptoms. It may need to be used every day for several weeks to months for it to help. Please read our Nasal Wash MedFact at http://www.nationaljewish.org/disease-info/treatments/alt-ther/nasal-wash.aspx for more information about this technique. Share this information with your doctor to see if you would benefit from this daily treatment.