Hmmm I am not sure if it could happen that quickly but you never know. Anyone else have exp? Maybe @TessaAndSamson or @sheshistory can help you in the ear department.
Do you put cotton in the ears while bathing? If any water, even a drop, gets into those ears it can cause a yeast takeover about a week or less later. Also food can be a yeast trigger in ears. Any change of diet in the past month?