I Had Swimmers Ear Two Months Ago. Received Corticosteroid/antibiotic Combo

I had swimmers ear two months ago. Received corticosteroid/antibiotic combo ear drops from a doctor. Pain went away after three days. I stopped using drops. Infection came back. I reused drops. Infection went away and came back. Two months later, now I am in the same battle. I got it looked at again and now there is white on my eardrum. Is this from using expired drops or from having a long battle with a bacterial infection?