Hello,
Phantom smell may be due to halitosis(due to infections of the oral cavity or poor hygiene),smell from the sweat or smell due to nasal or sinus infections.
I feel that an evaluation by an ENT specialist will be the best. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
How bad is the odor? Is it enough so other people smell you? Do you drink alcohol have a lot of skin infections or digestive disorders?
I used to have this problem too. I would use this electric shaver that I would rinse with water. Thing is the shaver started smelling bad. So I was rubbing on my face contaminated shaver. Anyway I'm also prone to fungal and yeast infections. The problem would also manifest if I sweat alot. I'm taking a lot of herbs so maybe that's helping a bit. Also I've eliminated Bread, lactose containing dairy, and excess starches from my diet.
-DK