Hi.
Well, it looks like Phantom smell that is experiencing smell that is not present or not being perceived by others.
As smell and taste are interrelated the sense of taste can also get affected.
It can occur due to a number of conditions like
nasal infection and polyps, migranes, Oral and dental infection, smoking habit, condition related to Nervous System ,
head injury etc..
As it begin after cold then it might be related to sinus problem.
I will suggest you to consult a Medicine Specialist or a
Neurologist and get evaluated and along with
clinical evaluation investigations like Nasal
endoscopy, MRI, etc can help in diagnosis and treatment can be planned accordingly..
As of now you can do saline
nasal irrigation, steam inhalation with few drops of Eucalyptus oil in water, chew flavoured sugar free chewing gum and limit intake of high aroma foods like onion and garlic..
Hope I have answered your query.
Please let me know if I can assist you further.
Regards.
Dr. Honey Arora. L