what was the name of the drug, which patient 52898 was last prescribed via right ear route since 02/2105?
select prescriptions.drug from prescriptions where prescriptions.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 52898 ) and prescriptions.route = 'right ear' and strftime('%y-%m',prescriptions.startdate) >= '2105-02' order by prescriptions.startdate desc limit 1