Suzanne

As Leslie pointed out you have been seeing an ENT all along, just using their fancy formal name rather than their colloquial designation. Yes, a simple CT scan is all that is really needed especially for diagnosing ear pain possibilities of cancer tumor. There is a reason why almost every PET scan is usually a combination of both PET and CT. PET scans just measure sugar intake, a highly unreliable diagnostic tool for cancers of the tongue, base of tongue and soft tissues in the oral cavity. The CT scan shows what is really there or not anatomically. If your CT scan is clear then it very improbable that the ear pain is being caused by cancer. An MRI would also be more accurate than any PETScan. It is a very reasonable request to have either a CT or MRI done in light of this symptom. Again, I would bet they will come out clear, but you need and deserve this peace of mind.
Charm