Capsaicin I understand is a good start to getting your sniffer back in order
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I’ve heard that, but I cook and use both jalapeño and habanero..no luck.
What about menthol cones? Had something many years ago that was similar to what you're going through, albeit not quite as severe.
Went to the UK the following month to visit some of my father's relatives, who took me to a chemist's (i.e., drugstore in America), and they had these lozenges, slightly cone-shaped, made of very strong menthol. They instructed me to rub it under my nose before going to bed daily. Two days later, my sense of smell began to return. It was fully functional again by the time I returned to the U.S.
Again, just a thought. It might work for you, or it might not. Good luck, regardless!
Might want to try it with high dose niacin.