There are many possibilities ranging from olfactory hallucinations to certain nasal infections. This cannot be identified over the net, only by examination by a doctor.
Go see your doctor.
Burning Wires.
burning rubber
That smell is probably your clutch burning out.
It depends what odour you mean. It's just a word we use to describe a particularly sharp smell. If you are referring to a person's smell, it usually is caused by bacteria breaking down sweat This is what causes that odour.
It must mean that are drinking to much alcoholic beverages,
Several thing scan cause a burning smell from a car A/C. One cause can be that the compressor is burning up. Another possibility is a wiring shortage.
take it easier on the clutch as your reversing
I think that we drink to much alcohol and our brains can handle drinking to much.
Friction from excessive braking causes heat, thus the lubricant on brakes release this burnt smell.
Most people say nothing about smells , a few say they smell flowers, and some , generally those with brain tumors, have outright olfactory hallucinations and smell everything from burning garbage to food cooking to sweet smells and revolting things.
The clutch is slipping and needs replaced.
Sometimes when parts are new, they have coatings and etc. that will smell when parts are warm. For example, alternator windings are coated with a electrical varnish. When the alternator is charging, it creates heat. This causes the paint to smell and odors such as a burning smell can be common for a couple of days.