I found long term use of Mometasone to have unpleasant side effects. Have you tried Montelukast, or spoken to an ENT consultant? A small surgical procedure eliminated nearly all of my symptoms.
I've not tried Montelukast (didn't even know about it, but I will look into it, thank you!), but I did have a surgery, which improved the situation somewhat, but only to a "I can breathe somewhat" level. I don't know its technical name, but it came with a general anaesthetic, lots of care afterwards, and a three-page invoice.