Careful with netipots. Tap water can have flesh eating bacteria, that can be fatal when introduced through the nose.
I have the same problem that I can not smell at all. Probiotics has helped, zinc and magnesium supplements and hcl betaine has helped too as far as I can tell. If anything magnesium, zinc and probiotics are important.
I have parasites too and they pass through when I eat extremely spicy food or take laxatives.