She presumably has seen an ENT surgeon and he ordered the scan.
If she has been seen surely a specialist or even a GP would look in the ear and rule out wax.
There are many causes of earache unilateral and it would be a fruitless effort to go into them all, some not even associated with the ear (referred pain).
She should see an ENT specialist and if she has, then one can go no further at the moment.
If she hasn't seen an ENT specialist then she should seek referral as this could either be a simple thing OR a big deal.