I hope that you don't mind me jumping in here. I used to do a lot of nasal sprays and they are one way to deaden sensations in your nose. It's very difficult to wean yourself off of them, but if you haven't yet I suggest that you do and, the sooner the better. You won't breathe well for a few days until the swelling goes down inside your nose. It's called a rebound effect: after using a drug for so long it actually turns around and does the actual opposite.

If there is no underlying medical cause then I would ask if there have been any changes in your life that would cause undo stress. In other words, has something changed?