I would highly suggest that you set up a visit with your primary care doctor
at your earliest convenience to discuss this issue. There are several potential medical problems that could lead to this problem.
First of all, I think it is important to rule out that you are really 'smelling something that isn't there.' For example, conditions like chronic sinus congestion, sinus infections, bad acid reflux
, and gum or tooth inflammation or infection may lead to a bad smell that only you notice (since it would be coming from your nose or throat). Your doctor can perform a careful physical exam to determine if you have any of these conditions and, if so, recommend an appropriate treatment.
Second, seizures can often lead to smelling smells that are not there; in particular seizures that come from the part of the brain that is called the temporal lobe can do this. If you have a history of seizure disorder or head injury you will want to discuss this with either your primary doctor or a neurologist
to make sure this is not what is going on.
Finally, rarely, disturbance in smell can be related to a very serious problem, such as a brain tumor; this is also something your doctor will consider and rule out.