I keep smelling weird smells that arent even their. it's been happening a lot lately. could i have a brain tumor?

Possible: There are many causes for changes to smells including drugs, alcohol, tobacco, heavy metals, head trauma, multiple sclerosis, parkinson's disease, frontal tumor, alzheimer's disease, korsakoff's psychosis, renal failure, hepatic failure, vitamin B12 deficiency, cushing's syndrome, hypothyroidism, diabetes mellitus, viral hepatitis, or even influenza. You should see your family practice physician.

See neurologist: Temporal lobe seizures can present with olfactory hallucinations or auras. A tumor can cause this, as can a history of prior head injuries. Take a good notes of your symptoms and have an evaluation by a neurologist who might be able to make a preliminary diagnosis based on the description of the symptoms. The neurologist may then get an mri.