Brief Answer:
Possible dry skin, a fungal infection or eczema.

Detailed Answer:
Hello,

Thank you for using HCM to post your health query.
I read carefully your question and I understand your concern.

By using the cortizone you have just treated the symptom of itching but not treated the problem.
To know for sure what its the problem, you may need a visit to an ENT doctor who can see inside your ear and understand what its happening.

The most common cause if itchiness in the ear it is dry skin of the external canal and a fungal infection. In the first case, you just need to avoid putting things inside the ear, and in the second case antifungal drops would be the cure. Maybe you have an eczema too and in this case using prednizone for a long time time would be the treatment.

Hope this is helpful.
Let me know if you need more clarifications.
Otherwise please close and rate the answer.

Regards,
Dr. Papaqako

---