Any associated dandruff in the hair ?
Since how long are you having these symptoms?
Have you seen a doctor ?
Any history of exposure to cold conditions?
Are the lesion limited to external ear ?( Pinna)
Does the symptoms started in the winters ?
Has the condition worsened in over a year ?
Have you been treated with anti fungal medication ?
Treatment history so far ?
In my opinion you need to be seen by a ENT specialist and to rule out the possibility of fungal infection of the ear canal and the external ear especially since you have not improved with antibiotics .
Topical and systemic antifungal treatment may be required .But before that a good ENT specialist should be considered for an evaluation .
Hope this helps