There could be a number of reasons that a doctor hopefully could find for you. For me, I found that if I was allergic to something, the nasal membranes would close shut.
For example, one time many years ago when I had serious medical problems (before I had my mercury fillings removed), I took bee pollen. First, this bee pollen would not let me sleep properly the second time I took it. Afterwards, I persisted in taking this bee pollen, because I knew it somehow benefited me. There were too many reasons for me to continue with this nutrient. Well, I did continue as I did with my herbs...and with this bee pollen for about six months my nasal membranes slammed shut.
It was such a relief when the nasal membranes opened up. I was so stubborn in those days, to try and find a cause for all of my medical troubles. About 10 years ago, I linked this to my mercury fillings when my tooth broke. I haven't taken bee pollen in about 10 years on a regular basis (the same time - I think it's been that long), but I do remember the reaction that I got with this bee pollen.
So for you, it could be a reaction of some sort from an allergen. Again, your doctor, hopefully will be your best hope in finding the cause and solution for you.